mark newly opened fds as FD_CLOEXEC (close on exec)

(This is iptables-1.4.3.1-cloexec.patch from RedHat iptables.src.rpm)

Signed-off-by: Maciej Zenczykowski <maze@google.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/iptables-xml.c b/iptables-xml.c
index 8d67056..57c7486 100644
--- a/iptables-xml.c
+++ b/iptables-xml.c
@@ -651,7 +651,7 @@
 	}
 
 	if (optind == argc - 1) {
-		in = fopen(argv[optind], "r");
+		in = fopen(argv[optind], "re");
 		if (!in) {
 			fprintf(stderr, "Can't open %s: %s", argv[optind],
 				strerror(errno));