qt5imageformats: needs gui support in qt5base

Fixes http://autobuild.buildroot.net/results/8843619e91958766c66c0955f363bbfc733b31e6/build-end.log

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/qt5/qt5imageformats/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_QT5IMAGEFORMATS
 	bool "qt5imageformats"
 	select BR2_PACKAGE_QT5BASE
+	select BR2_PACKAGE_QT5BASE_GUI
 	help
 	  Qt is a cross-platform application and UI framework for
 	  developers using C++.