Some qmake tests in qwebkit module need fixes

When building qwebkit we pass throw some tests for find thirdparty libraries such as libxml2, libxslt, libjpeg, libpng, fontconfig. I attach my qmodule.pri file where I have added INCLUDEPATH and LIBS that pointed to needed libraries but qmake tests doesn't use them. Next issue that I saw in qt5\qtwebkit\Tools\qmake\config.tests\libxml2\libxml2.cpp that use header <libxml2/libxml/xmlreader.h> but need to use as <libxml/xmlreader.h> because "pkg-config --cflags libxml-2.0" usually return something like "-I/usr/include/libxml2"