clear TESTS variable between subdirs

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@12866 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

Makefile

@@ -50,7 +50,7 @@ $(PROGS): %$(EXESUF): %_g$(EXESUF)
 	cp -p $< $@
 	$(STRIP) $@
 
-SUBDIR_VARS := OBJS ASM_OBJS CPP_OBJS FFLIBS CLEANFILES DIRS
+SUBDIR_VARS := OBJS ASM_OBJS CPP_OBJS FFLIBS CLEANFILES DIRS TESTS
 
 define RESET
 $(1) :=