Added a filter rule for filtering make output with
tools/winapi/make_filter.

diff --git a/Make.rules.in b/Make.rules.in
index 2b07bb2..a168fc4 100644
--- a/Make.rules.in
+++ b/Make.rules.in
@@ -204,6 +204,9 @@
 
 all: Makefile
 
+filter:
+	@$(TOPSRCDIR)/tools/winapi/make_filter --make $(MAKE) all
+
 # Rule for main module intermediate object
 
 $(MODULE).tmp.o: $(OBJS) Makefile.in