mesa: refactor: move #define FEATURE flags into new mfeatures.h file

Also, check the FEATURE flags in many places.
(cherry picked from commit 40d1a40f294f1ed2dacfad6f5498322fc08cc2d1)

Conflicts:

	src/mesa/main/config.h
	src/mesa/main/context.c
	src/mesa/main/texobj.c
	src/mesa/main/texstate.c
	src/mesa/main/texstore.c
16 files changed