Added glesv2 and glesv1_cm pkgconfig files.
Added patch on Qt5GuiConfigExtras.cmake.in.
This patch adds /usr/include to the _GL_INCDIRS search paths.
Without this explicit configuration, Qt5GuiConfigExtras.cmake ignores
/usr/include while looking for GLESV2 header files, even when it is defined
in pkgconfig files.