Add missing module alias. This is a must to load ctnetlink on demand. For 
example, the conntrack tool will fail if the module isn't loaded.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Index: net-2.6.git/net/ipv4/netfilter/ip_conntrack_netlink.c
===================================================================
--- net-2.6.git.orig/net/ipv4/netfilter/ip_conntrack_netlink.c	2005-11-04 17:55:24.000000000 +0100
+++ net-2.6.git/net/ipv4/netfilter/ip_conntrack_netlink.c	2005-11-04 18:31:04.000000000 +0100
@@ -1538,6 +1538,8 @@ static struct nfnetlink_subsystem ctnl_e
 	.cb				= ctnl_exp_cb,
 };
 
+MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK);
+
 static int __init ctnetlink_init(void)
 {
 	int ret;