netfilter: cttimeout: add netns support

Add a per-netns list of timeout objects and adjust code to use it.

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

include/net/net_namespace.h

@@ -121,6 +121,9 @@ struct net {
 #if IS_ENABLED(CONFIG_NETFILTER_NETLINK_ACCT)
 	struct list_head        nfnl_acct_list;
 #endif
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
+	struct list_head	nfct_timeout_list;
+#endif
 #endif
 #ifdef CONFIG_WEXT_CORE
 	struct sk_buff_head	wext_nlevents;