mesa: use sources.mak -- need to figure out how to support non-gallium builds also

src/mesa/Makefile

@@ -3,7 +3,7 @@
 TOP = ../..
 include $(TOP)/configs/current
 
-include sources
+include sources.mak
 
 .SUFFIXES : .cpp
 

src/mesa/Makefile.mgw

@@ -124,7 +124,7 @@ ifneq ($(wildcard $(addsuffix /rm,$(subst :, ,$(PATH)))),)
 UNLINK = $(RM) $(1)
 endif
 
-include sources
+include sources.mak
 
 CFLAGS += $(INCLUDE_DIRS)