secmark: fix config problem when CONFIG_NF_CONNTRACK_SECMARK is not set

When CONFIG_NF_CONNTRACK_SECMARK is not set we accidentally attempt to use
the secmark fielf of struct nf_conn.  Problem is when that config isn't set
the field doesn't exist.  whoops.  Wrap the incorrect usage in the config.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

net/netfilter/nf_conntrack_netlink.c

@@ -582,9 +582,11 @@ ctnetlink_conntrack_event(unsigned int events, struct nf_ct_event *item)
 		    && ctnetlink_dump_helpinfo(skb, ct) < 0)
 			goto nla_put_failure;
 
+#ifdef CONFIG_NF_CONNTRACK_SECMARK
 		if ((events & (1 << IPCT_SECMARK) || ct->secmark)
 		    && ctnetlink_dump_secctx(skb, ct) < 0)
 			goto nla_put_failure;
+#endif
 
 		if (events & (1 << IPCT_RELATED) &&
 		    ctnetlink_dump_master(skb, ct) < 0)