Return 'errno' value from the table_do_modify_record(), it is expected

by table_modify_record().

This makes quiet operations with tables really quiet.

PR:		222953
MFC after:	1 week

sbin/ipfw/tables.c

@@ -885,6 +885,8 @@ table_do_modify_record(int cmd, ipfw_obj_header *oh,
 
 	sz += sizeof(*oh);
 	error = do_get3(cmd, &oh->opheader, &sz);
+	if (error != 0)
+		error = errno;
 	tent = (ipfw_obj_tentry *)(ctlv + 1);
 	/* Copy result back to provided buffer */
 	memcpy(tent_base, ctlv + 1, sizeof(*tent) * count);