Clear some more variables that are used on subdir Makefiles.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@18180 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

Makefile

@@ -47,7 +47,8 @@ $(PROGS): %$(EXESUF): %_g$(EXESUF)
 	cp -p $< $@
 	$(STRIP) $@
 
-SUBDIR_VARS := OBJS FFLIBS CLEANFILES DIRS TESTPROGS EXAMPLES
+SUBDIR_VARS := OBJS FFLIBS CLEANFILES DIRS TESTPROGS EXAMPLES \
+               ALTIVEC-OBJS MMX-OBJS YASM-OBJS-FFT YASM-OBJS
 
 define RESET
 $(1) :=