Move the sub-architecture feature to better places in qmake

Move the sub-architecture feature to better places in qmake

Instead of saving the ability of the compiler to produce SSE2, AVX,
Neon, etc. code in .qmake.cache (Unix) or qconfig.pri (Windows), move
everything to qmodule.pri. Accordingly, move the DEFINES += settings
to qt_module.prf instead of qt.prf.

This allows us to re-use these settings in other Qt modules (other
than qtbase), if necessary. Though currently the extra compiler
definitions are found only in src/gui/gui.pro. They can be moved
elsewhere when it becomes necessary.

As a side-effect of this change, some other flags are moved from
.qmake.cache to qmodule.pri (on Unix). The flags that are getting
moved should probably be moved anyway.

Change-Id: Ibc3ab0111e148d81870772f9357273660aa93417
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>