Makfile: move suffix rules to Makefile.build

This commit moves suffix rules from config.mk
to scripts/Makefile.build, which will allow us
to switch smoothly to real Kbuild.

Note1:
post/lib_powerpc/fpu/Makefile has
its own rule to compile C sources.
We need to tweak it to keep the same behavior.

Note2:
There are two file2 with the same name:
arch/arm/lib/crt0.S and eamples/api/crt0.S.
To keep the same build behavior,
examples/api/Makefile also has to be treaked.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/post/lib_powerpc/fpu/Makefile b/post/lib_powerpc/fpu/Makefile
index ae56a82..a7aa5bc 100644
--- a/post/lib_powerpc/fpu/Makefile
+++ b/post/lib_powerpc/fpu/Makefile
@@ -18,7 +18,7 @@
 CFLAGS := $(shell echo $(CFLAGS) | sed s/-msoft-float//)
 CFLAGS += -mhard-float -fkeep-inline-functions
 
-$(obj)%.o:	%.c
+$(addprefix $(obj),$(obj-y)): $(obj)%.o:	%.c
 	$(CC)  $(ALL_CFLAGS) -o $@.fp $< -c
 	$(OBJCOPY) -R .gnu.attributes $@.fp $@
 	rm -f $@.fp