Finish up ATI_separate_stencil

Add entrypoints to glapi XML file and regenerate files.
Implement glStencilOpSeparateATI().
Consolidate some code in stencil.c

Conflicts:

	src/mesa/glapi/dispatch.h
	src/mesa/glapi/glapioffsets.h
	src/mesa/glapi/glapitable.h
	src/mesa/glapi/glapitemp.h
	src/mesa/glapi/glprocs.h
	src/mesa/main/enums.c
	src/mesa/main/state.c
	src/mesa/sparc/glapi_sparc.S
	src/mesa/x86-64/glapi_x86-64.S
	src/mesa/x86/glapi_x86.S