.prl and .pc files require linking to libs which are private to webkit

The prl and pc files are indicating the need of linking against xslt, lgio and others which are definitely private dependencies. So stuff building against webkit will needlessly need to install this libs to needlessly link against it.

$ grep -iRn lxslt *
usr/lib/x86_64-linux-gnu/pkgconfig/Qt5WebKit.pc:11:Libs.private: -L/usr/X11R6/lib64 -lQt5Network -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Gui -L/usr/X11R6/lib64 -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Core -lpthread -lpthread -Wl,-whole-archive -lWebKit1 -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/WebKit/ -Wl,-whole-archive -lWebKit2 -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/WebKit2/ -lrt -Wl,-whole-archive -lWebCore -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/WebCore/ -lz -lXrender -lXcomposite -lXrender -ljpeg -lpng -lwebp -Wl,-whole-archive -lANGLE -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/ThirdParty/ANGLE/ -Wl,-whole-archive -lJavaScriptCore -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/JavaScriptCore/ -Wl,-whole-archive -lWTF -Wl,-no-whole-archive -L/build/qtwebkit-opensource-src-VV8IJ_/qtwebkit-opensource-src-5.2.0+dfsg/Source/WTF/ -licui18n -licuuc -licudata -lXext -lX11 -lm -lX11 -lxslt -lxml2 -lxml2 -lglib-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0 -pthread -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstapp-0.10 -lgstbase-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstbase-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstinterfaces-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstpbutils-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -pthread -lgstvideo-0.10 -lgstbase-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -lsqlite3 -lQt5Quick -L/usr/X11R6/lib64 -L/usr/lib/x86_64-linux-gnu -lQt5Qml -lQt5Network -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -L/usr/lib/x86_64-linux-gnu -lQt5Network -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Gui -L/usr/X11R6/lib64 -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Core -lpthread -lpthread -lQt5Qml -lQt5Network -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Sql -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Gui -L/usr/X11R6/lib64 -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Network -L/usr/lib/x86_64-linux-gnu -lQt5Core -lpthread -lpthread -lQt5Core -lpthread -lGL
usr/lib/x86_64-linux-gnu/pkgconfig/Qt5WebKitWidgets.pc:11:Libs.private: -L/usr/X11R6/lib64 -lX11 -lxslt -lgio-2.0 -lgstapp-0.10 -lgstinterfaces-0.10 -lgstpbutils-0.10 -pthread -lgstvideo-0.10 -lgstbase-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -lsqlite3 -lQt5Quick -L/usr/lib/x86_64-linux-gnu -lQt5OpenGL -lQt5PrintSupport -L/usr/lib/x86_64-linux-gnu -lQt5WebKit -lQt5Qml -lQt5Widgets -lQt5Sql -lQt5Network -lQt5Gui -lQt5Core -lpthread -lXext -lX11 -lm -lGL
usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.prl:6:QMAKE_PRL_LIBS = -L/usr/X11R6/lib64 -lX11 -lxslt -lgio-2.0 -lgstapp-0.10 -lgstinterfaces-0.10 -lgstpbutils-0.10 -pthread -lgstvideo-0.10 -lgstbase-0.10 -lgstreamer-0.10 -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0 -lxml2 -lglib-2.0 -lsqlite3 -lQt5Quick -L/usr/lib/x86_64-linux-gnu -lQt5OpenGL -lQt5PrintSupport -L/usr/lib/x86_64-linux-gnu -lQt5WebKit -lQt5Qml -lQt5Widgets -lQt5Sql -lQt5Network -lQt5Gui -lQt5Core -lpthread
grep: usr/lib/x86_64-linux-gnu/libQt5WebKitWidgets.so: No such file or directory
grep: usr/lib/x86_64-linux-gnu/libQt5WebKit.so: No such file or directory