Fix brief make messages when CC etc are specified on command line

Originally committed as revision 23792 to svn://svn.ffmpeg.org/ffmpeg/trunk

common.mak

@@ -26,8 +26,8 @@ SILENT = DEPCC YASMDEP RM RANLIB
 MSG    = $@
 M      = @$(call ECHO,$(TAG),$@);
 $(foreach VAR,$(BRIEF), \
-    $(eval $(VAR) = @$$(call ECHO,$(VAR),$$(MSG)); $($(VAR))))
-$(foreach VAR,$(SILENT),$(eval $(VAR) = @$($(VAR))))
+    $(eval override $(VAR) = @$$(call ECHO,$(VAR),$$(MSG)); $($(VAR))))
+$(foreach VAR,$(SILENT),$(eval override $(VAR) = @$($(VAR))))
 $(eval INSTALL = @$(call ECHO,INSTALL,$$(^:$(SRC_DIR)/%=%)); $(INSTALL))
 endif