package/xscreensaver: add gl dependency

Fix the following build failure without gl raised since bump to version
6.03 in commit cbcbd66b0f241184288232972d9cd9d03c9f0ce1:

       Note: The OpenGL 3D library is not being used.

             Those demos which use 3D will not be built or installed.
             That is most of them.

make: *** [package/pkg-generic.mk:282: /home/peko/autobuild/instance-0/output-1/build/xscreensaver-6.03/.stamp_configured] Error 1

A patch was sent to Jamie Zawinski to fix this failure and he replied:

"Why would you do that? I pretty much consider that an unsupported
configuration, since that's more than half of the savers at this point."

I told him that some embedded devices don't have gl and he replied:

"Such as? Just about every modern "embedded device" I'm aware of is more
performant than the desktop computers on which I developed many of those
GL hacks..."

So just add a dependency on gl.

Fixes:
 - http://autobuild.buildroot.org/results/b76743a48d75b5b7539712318fa0b2937a157f88

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[yann.morin.1998@free.fr: keep --with-gl=yes]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/xscreensaver/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_XSCREENSAVER
 	bool "xscreensaver"
 	depends on BR2_PACKAGE_XORG7
+	depends on BR2_PACKAGE_HAS_LIBGL # libglu
 	depends on BR2_INSTALL_LIBSTDCPP # libgtk2 -> pango
 	depends on BR2_TOOLCHAIN_HAS_THREADS # gdk-pixbuf, libgtk2 -> glib2
 	depends on BR2_USE_WCHAR # gdk-pixbuf, libgtk2 -> glib2
@@ -9,7 +10,7 @@ config BR2_PACKAGE_XSCREENSAVER
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # libgtk2 -> pango -> harfbuzz
 	select BR2_PACKAGE_GDK_PIXBUF
 	select BR2_PACKAGE_GDK_PIXBUF_XLIB
-	select BR2_PACKAGE_LIBGLU if BR2_PACKAGE_HAS_LIBGL
+	select BR2_PACKAGE_LIBGLU
 	select BR2_PACKAGE_LIBGTK2
 	select BR2_PACKAGE_LIBXML2
 	select BR2_PACKAGE_JPEG
@@ -28,10 +29,10 @@ config BR2_PACKAGE_XSCREENSAVER
 
 	  http://www.jwz.org/xscreensaver/
 
-comment "xscreensaver needs a toolchain w/ wchar, C++, threads, gcc >= 4.9"
+comment "xscreensaver needs a toolchain w/ wchar, C++, threads, gcc >= 4.9, OpenGL backend"
 	depends on BR2_PACKAGE_XORG7
 	depends on BR2_USE_MMU
 	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS || \
 		!BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 || \
-		!BR2_USE_WCHAR
+		!BR2_USE_WCHAR || !BR2_PACKAGE_HAS_LIBGL

package/xscreensaver/xscreensaver.mk

@@ -17,6 +17,8 @@ XSCREENSAVER_DEPENDENCIES = \
 	gdk-pixbuf \
 	gdk-pixbuf-xlib \
 	jpeg \
+	libgl \
+	libglu \
 	libgtk2 \
 	libxml2 \
 	xlib_libX11 \
@@ -30,14 +32,8 @@ XSCREENSAVER_DEPENDENCIES = \
 # compiler/linker
 XSCREENSAVER_CONF_OPTS = \
 	--includedir=$(STAGING_DIR)/usr/include \
-	--libdir=$(STAGING_DIR)/usr/lib
-
-ifeq ($(BR2_PACKAGE_HAS_LIBGL),y)
-XSCREENSAVER_CONF_OPTS += --with-gl=yes
-XSCREENSAVER_DEPENDENCIES += libgl libglu
-else
-XSCREENSAVER_CONF_OPTS += --with-gl=no
-endif
+	--libdir=$(STAGING_DIR)/usr/lib \
+	--with-gl=yes
 
 ifeq ($(BR2_PACKAGE_LIBPNG),y)
 XSCREENSAVER_CONF_OPTS += --with-png=yes