Add rule for compiling to asm

This allows commands of the form "make foo.s", which is useful
for inspecting the compiler output for debugging purposes.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

common.mak

@@ -47,6 +47,9 @@ COMPILE_S = $(call COMPILE,AS)
 %.o: %.cpp
 	$(COMPILE_CXX)
 
+%.s: %.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) -S -o $@ $<
+
 %.o: %.S
 	$(COMPILE_S)
 

subdir.mak

@@ -20,7 +20,7 @@ $(SUBDIR)x86/%.o: $(SUBDIR)x86/%.asm
 	$(YASMDEP) $(YASMFLAGS) -I $(<D)/ -M -o $@ $< > $(@:.o=.d)
 	$(YASM) $(YASMFLAGS) -I $(<D)/ -o $@ $<
 
-$(OBJS) $(SUBDIR)%.ho $(TESTOBJS): CPPFLAGS += -DHAVE_AV_CONFIG_H
+$(OBJS) $(OBJS:.o=.s) $(SUBDIR)%.ho $(TESTOBJS): CPPFLAGS += -DHAVE_AV_CONFIG_H
 $(TESTOBJS): CPPFLAGS += -DTEST
 
 $(SUBDIR)$(LIBNAME): $(OBJS)