Make sure sed fixups are carried out

The following issue is possibly caused by using busybox make.

protobuf/packet-sock.pb-c.c: In function 'packet_sock_entry__init':
protobuf/packet-sock.pb-c.c:98:3: error: this decimal constant is unsigned only in ISO C90 [-Werror]

Use a belt-and-suspenders approach to ensure it doesn't happen.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

protobuf/Makefile

@@ -86,7 +86,9 @@ $(obj)/%.pb-c.c $(obj)/%.pb-c.h: $(obj)/%.proto $(obj)/%.proto.c.d
 	$(E) "  PBCC    " $@
 	$(Q) protoc-c --proto_path=$(obj)/ --c_out=$(obj)/ $<
 ifeq ($(ARCH),arm)
-	$(Q) sed -i -e 's/4294967295/0xFFFFFFFF/g' $@ $(patsubst %.h,%.c,$@)
+	$(Q) sed -i -e 's/4294967295/0xFFFFFFFF/g' $@
+	$(Q) sed -i -e 's/4294967295/0xFFFFFFFF/g' $(patsubst %.c,%.h,$@)
+	$(Q) sed -i -e 's/4294967295/0xFFFFFFFF/g' $(patsubst %.h,%.c,$@)
 endif
 
 $(obj)/%.o: $(obj)/%.pb-c.c $(obj)/%.pb-c.h