netfilter: ctnetlink: fix compilation without NAT support

This patch fixes the compilation of ctnetlink when the NAT support
is not enabled.

/home/benh/kernels/linux-powerpc/net/netfilter/nf_conntrack_netlink.c:819: warning: enum nf_nat_manip_type\u2019 declared inside parameter list
/home/benh/kernels/linux-powerpc/net/netfilter/nf_conntrack_netlink.c:819: warning: its scope is only this definition or declaration, which is probably not what you want

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

Index: net-next-2.6/net/netfilter/nf_conntrack_netlink.c
===================================================================
--- net-next-2.6.orig/net/netfilter/nf_conntrack_netlink.c	2008-10-17 14:15:26.000000000 +0200
+++ net-next-2.6/net/netfilter/nf_conntrack_netlink.c	2008-10-17 14:17:12.000000000 +0200
@@ -814,6 +814,7 @@
 	return err;
 }
 
+#ifdef CONFIG_NF_NAT_NEEDED
 static int
 ctnetlink_parse_nat_setup(struct nf_conn *ct,
 			  enum nf_nat_manip_type manip,
@@ -841,6 +842,7 @@
 
 	return parse_nat_setup(ct, manip, attr);
 }
+#endif
 
 static int
 ctnetlink_change_status(struct nf_conn *ct, struct nlattr *cda[])