xtables-standalone: call nft_fini in the error path

This error is shown with valgrind tools:

valgrind --leak-check=full xtables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT

==7377== 16 bytes in 1 blocks are still reachable in loss record 1 of 14
==7377==    at 0x4C2B514: calloc (vg_replace_malloc.c:593)
==7377==    by 0x574CC76: mnl_socket_open (socket.c:117)
==7377==    by 0x417495: nft_init (nft.c:598)
==7377==    by 0x4134C2: xtables_main (xtables-standalone.c:64)
==7377==    by 0x5B87994: (below main) (libc-start.c:260)

This patch calls nft_fini to release the objects that have been allocated in
nft_init. This function was not used so far.

Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/iptables/xtables-standalone.c b/iptables/xtables-standalone.c
index cb685d6..c9f8e15 100644
--- a/iptables/xtables-standalone.c
+++ b/iptables/xtables-standalone.c
@@ -66,6 +66,7 @@
 				xtables_globals.program_name,
 				xtables_globals.program_version,
 				strerror(errno));
+		nft_fini(&h);
 		exit(EXIT_FAILURE);
 	}
 
@@ -73,6 +74,8 @@
 	if (ret)
 		ret = nft_commit(&h);
 
+	nft_fini(&h);
+
 	if (!ret) {
 		if (errno == EINVAL) {
 			fprintf(stderr, "iptables: %s. "