package/qt5/qt5webengine: use bundled jpeg-turbo for chromium

The configure flag -feature-webengine-system-jpeg[1] checks if a jpeg
library is in the sysroot.

It compiles a test file linked against the symbols jpeg_crop_scanline()
and jpeg_skip_scanlines()[2] that are specific to jpep-turbo.

As a consequence, the configure scripts fails if the libjpeg is selected
as the jpeg variant as the symbols mentionend above are not part of the
jpeg library installed in the sysroots.

	ERROR: Feature 'webengine-system-jpeg' was enabled, but the pre-condition 'config.unix && features.system-jpeg && libs.webengine-jpeglib' failed.

Additionally, see the log below, extracted from config.log:

        > /home/gportay/src/buildroot/output/host/bin/arm-buildroot-linux-gnueabihf-g++ -c -pipe -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g0 -D_FORTIFY_SOURCE=1 -mtune=arm1176jzf-s -march=armv6 --sysroot=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot -w -fPIC  -I. -I/home/gportay/src/buildroot/output/host/mkspecs/devices/linux-buildroot-g++ -o main.o main.cpp
        > main.cpp: In function ‘int main(int, char**)’:
        > main.cpp:12:5: error: ‘jpeg_crop_scanline’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
        >    12 |     jpeg_crop_scanline(nullptr, &dummy, &dummy);
        >       |     ^~~~~~~~~~~~~~~~~~
        >       |     jpeg_write_scanlines
        > main.cpp:13:5: error: ‘jpeg_skip_scanlines’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
        >    13 |     jpeg_skip_scanlines(nullptr, dummy);
        >       |     ^~~~~~~~~~~~~~~~~~~
        >       |     jpeg_write_scanlines
        > make[1]: *** [Makefile:334: main.o] Error 1
        > make[1]: Leaving directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'

We could build some complicated logic to make sure what qt5webengine is
only used with jpeg-turbo. However, Chromium bundles jpeg-turbo[3][4]
and uses it if not using the system jpeg library or qt-jpeg[5]. It is
simpler to just always use that version instead of the system jpeg
library.

This sets the configure option -nofeature-webengine-system-jpeg and
removes jpeg from the dependencies.

Note that host-libjpeg and qt-jpeg (and therefore, system libjpeg or
jpeg-turbo) are still needed for the Qt integration layer, even if
chromium uses the bundled jpeg-turbo.

[1]: https://github.com/qt/qtwebengine/blob/v5.15.14-lts/src/buildtools/configure.json#L609-L613
[2]: https://github.com/qt/qtwebengine/blob/v5.15.14-lts/src/buildtools/configure.json#L95-L116
[3]: https://github.com/qt/qtwebengine-chromium/tree/18c9261dc5b8aa57a0bdd5b62ce6f648cca1ef5e/chromium/third_party/libjpeg_turbo
[4]: https://github.com/qt/qtwebengine-chromium/blob/18c9261dc5b8aa57a0bdd5b62ce6f648cca1ef5e/chromium/third_party/libjpeg.gni
[5]: https://github.com/qt/qtwebengine/blob/v5.15.14-lts/src/buildtools/configure.json#L614-618

Fixes:

	looking for library webengine-jpeglib
	Trying source 0 (type pkgConfig) of library webengine-jpeglib ...
	+ PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/pkg-config --exists --silence-errors libjpeg
	+ PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/pkg-config --modversion libjpeg
	> 9.6.0
	+ PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/pkg-config --libs-only-L libjpeg
	> -L/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib
	+ PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/pkg-config --libs-only-l libjpeg
	> -ljpeg
	+ PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/pkg-config --cflags libjpeg
	> -I/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/include
	+ cd /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib && PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += shared warn_off console single_arch" -early "CONFIG += cross_compile" 'QMAKE_USE += webengine-jpeglib' 'QMAKE_LIBS_WEBENGINE_JPEGLIB = -L/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib -ljpeg' /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib
	+ cd /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib && MAKEFLAGS= make
	> make[1]: Entering directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	> /home/gportay/src/buildroot/output/host/bin/arm-buildroot-linux-gnueabihf-g++ -c -pipe -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g0 -D_FORTIFY_SOURCE=1 -mtune=arm1176jzf-s -march=armv6 --sysroot=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot -w -fPIC  -I. -I/home/gportay/src/buildroot/output/host/mkspecs/devices/linux-buildroot-g++ -o main.o main.cpp
	> main.cpp: In function ‘int main(int, char**)’:
	> main.cpp:12:5: error: ‘jpeg_crop_scanline’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
	>    12 |     jpeg_crop_scanline(nullptr, &dummy, &dummy);
	>       |     ^~~~~~~~~~~~~~~~~~
	>       |     jpeg_write_scanlines
	> main.cpp:13:5: error: ‘jpeg_skip_scanlines’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
	>    13 |     jpeg_skip_scanlines(nullptr, dummy);
	>       |     ^~~~~~~~~~~~~~~~~~~
	>       |     jpeg_write_scanlines
	> make[1]: *** [Makefile:334: main.o] Error 1
	> make[1]: Leaving directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	 => source failed verification.
	Trying source 1 (type inline) of library webengine-jpeglib ...
	+ cd /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib && PKG_CONFIG_SYSROOT_DIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot PKG_CONFIG_LIBDIR=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/share/pkgconfig:/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/arm-buildroot-linux-gnueabihf/pkgconfig /home/gportay/src/buildroot/output/host/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += shared warn_off console single_arch" -early "CONFIG += cross_compile" 'QMAKE_USE += webengine-jpeglib' 'QMAKE_LIBS_WEBENGINE_JPEGLIB = -ljpeg' /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib
	+ cd /home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib && MAKEFLAGS= make clean && MAKEFLAGS= make
	> make[1]: Entering directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	> rm -f main.o
	> rm -f *~ core *.core
	> make[1]: Leaving directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	> make[1]: Entering directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	> /home/gportay/src/buildroot/output/host/bin/arm-buildroot-linux-gnueabihf-g++ -c -pipe -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g0 -D_FORTIFY_SOURCE=1 -mtune=arm1176jzf-s -march=armv6 --sysroot=/home/gportay/src/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot -w -fPIC  -I. -I/home/gportay/src/buildroot/output/host/mkspecs/devices/linux-buildroot-g++ -o main.o main.cpp
	> main.cpp: In function ‘int main(int, char**)’:
	> main.cpp:12:5: error: ‘jpeg_crop_scanline’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
	>    12 |     jpeg_crop_scanline(nullptr, &dummy, &dummy);
	>       |     ^~~~~~~~~~~~~~~~~~
	>       |     jpeg_write_scanlines
	> main.cpp:13:5: error: ‘jpeg_skip_scanlines’ was not declared in this scope; did you mean ‘jpeg_write_scanlines’?
	>    13 |     jpeg_skip_scanlines(nullptr, dummy);
	>       |     ^~~~~~~~~~~~~~~~~~~
	>       |     jpeg_write_scanlines
	> make[1]: *** [Makefile:334: main.o] Error 1
	> make[1]: Leaving directory '/home/gportay/src/buildroot/output/build/qt5webengine-5.15.14/config.tests/webengine-jpeglib'
	 => source failed verification.
	test config.qtwebengine_buildtools.libraries.webengine-jpeglib FAILED

Signed-off-by: Gaël PORTAY <gael.portay@rtone.fr>
[Arnout: always use the bundled jpeg-turbo]
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>

package/qt5/qt5webengine/qt5webengine.mk

@@ -71,7 +71,6 @@ QT5WEBENGINE_DEPENDENCIES += \
 	host-webp \
 	host-zlib \
 	freetype \
-	jpeg \
 	lcms2 \
 	libevent \
 	libnss \
@@ -96,7 +95,6 @@ QT5WEBENGINE_CONF_OPTS += \
 	-feature-webengine-system-glib \
 	-feature-webengine-system-glibc \
 	-feature-webengine-system-harfbuzz \
-	-feature-webengine-system-jpeg \
 	-feature-webengine-system-khr \
 	-feature-webengine-system-lcms2 \
 	-feature-webengine-system-libevent \
@@ -119,6 +117,7 @@ QT5WEBENGINE_CONF_OPTS += \
 	-no-feature-webengine-developer-build \
 	-no-feature-webengine-full-debug-info \
 	-no-feature-webengine-native-spellchecker \
+	-no-feature-webengine-system-jpeg \
 	-no-feature-webengine-system-minizip \
 	-no-feature-webengine-system-gn