make: protobuf -- Mangle integer constant on ARM only

It's known to work on x86-64 so make the build procedure
a bit faster here.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

protobuf/Makefile

@@ -51,7 +51,9 @@ PROTO_OBJS	:= $(patsubst %.c,%.o,$(PROTO_SRCS))
 %.pb-c.c %.pb-c.h: %.proto
 	$(E) "  PROTOBUF "$@
 	$(Q) protoc-c --c_out=./ $<
+ifeq ($(ARCH),arm)
 	$(Q) sed -i 's/4294967295/0xFFFFFFFF/g' $@ $(patsubst %c,%h,$@)
+endif
 
 %.o: %.c %.h
 	$(E) "  CC       "$@