[Makefile] Don't depend on locale settings when parsing readelf

Makefile.rules

@@ -113,4 +113,4 @@ quiet_cmd_objcopy = [ $@ ]
 # check_no_reloc
 # This depends on the output of readelf command.
 quiet_cmd_check_no_reloc = [ $@ ]
-      cmd_check_no_reloc = readelf -r $^ | grep -q 'There are no relocations in this file.'
+      cmd_check_no_reloc = LC_ALL=C readelf -r $^ | grep -q 'There are no relocations in this file.'