package/qt5/qt5webkit: widgets are mandatory

Fix the following build failure raised since bump to version
5.212.0-alpha4 in commit df0b0fe6919c0d0f3750f439a3cfa765232bd569:

CMake Error at /home/fabrice/buildroot/output/host/arm-buildroot-linux-gnueabihf/sysroot/usr/lib/cmake/Qt5/Qt5Config.cmake:28 (find_package):
  Could not find a package configuration file provided by "Qt5Widgets" with
  any of the following names:

    Qt5WidgetsConfig.cmake
    qt5widgets-config.cmake

  Add the installation prefix of "Qt5Widgets" to CMAKE_PREFIX_PATH or set
  "Qt5Widgets_DIR" to a directory containing one of the above files.  If
  "Qt5Widgets" provides a separate development package or SDK, be sure it has
  been installed.
Call Stack (most recent call first):
  Source/cmake/OptionsQt.cmake:646 (find_package)
  Source/cmake/WebKitCommon.cmake:51 (include)
  CMakeLists.txt:137 (include)

Fixes:
 - No autobuilder failures (yet)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Adam Duskett <aduskett@gmail.com>
Tested-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/qt5/qt5webkit/Config.in

@@ -17,6 +17,7 @@ config BR2_PACKAGE_QT5WEBKIT
 	select BR2_PACKAGE_LIBPNG
 	select BR2_PACKAGE_QT5BASE_ICU
 	select BR2_PACKAGE_QT5BASE_GUI
+	select BR2_PACKAGE_QT5BASE_WIDGETS
 	select BR2_PACKAGE_QT5LOCATION
 	select BR2_PACKAGE_QT5SENSORS
 	select BR2_PACKAGE_QT5WEBCHANNEL