[build] Move all the compiler flags to AM_CFLAGS

The INCLUDES directive should only contain pre-processor flags, since
we're passing it also to the introspection scanner.

Using AM_CFLAGS for compiler flags, like debug flags and maintainer
flags, is more indicated.

clutter/Makefile.am

@@ -33,11 +33,9 @@ INCLUDES = \
 	-DG_DISABLE_DEPRECATED 				\
 	-DG_LOG_DOMAIN=\"Clutter\" 			\
 	$(CLUTTER_CFLAGS) 				\
-	$(CLUTTER_DEBUG_CFLAGS)				\
-	$(MAINTAINER_CFLAGS)				\
 	$(NULL)
 
-AM_CFLAGS=$(GCC_FLAGS)
+AM_CFLAGS = $(GCC_FLAGS) $(CLUTTER_DEBUG_CFLAGS) $(MAINTAINER_CFLAGS)
 
 LDADD = \
 	$(CLUTTER_LT_LDFLAGS) \