ebtables: fixes from upstream

- libebtc: Fix an issue that '--concurrent' doesn't work with NFS: https://git.netfilter.org/ebtables/commit/?id=d696eb94e1ed49b1fce8c2da47aedbe9972cbf86
- ebtables: Spewing an error if --concurrent isn't first argument: https://git.netfilter.org/ebtables/commit/?id=52f88f8c22aae3b33f08865f2de659f8a9c4fa5c

release/src-rt-6.x.4708/router/ebtables/ebtables.c

@@ -1041,6 +1041,8 @@ big_iface_length:
 			strcpy(replace->filename, optarg);
 			break;
 		case 13 : /* concurrent */
+			if (OPT_COMMANDS)
+				ebt_print_error2("Please put the --concurrent option first");
 			use_lockfd = 1;
 			break;
 		case 1 :

release/src-rt-6.x.4708/router/ebtables/libebtc.c

@@ -144,7 +144,7 @@ static int lock_file()
 	int fd, try = 0;
 
 retry:
-	fd = open(LOCKFILE, O_CREAT|O_CLOEXEC, 00600);
+	fd = open(LOCKFILE, O_CREAT|O_WRONLY|O_CLOEXEC, 00600);
 	if (fd < 0) {
 		if (try == 1 || mkdir(dirname(pathbuf), 00700))
 			return -2;