netfilter: nfnetlink: netns support

Make nfnl socket per-petns.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index f307e13..82b7be4 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -81,6 +81,8 @@
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	struct netns_ct		ct;
 #endif
+	struct sock		*nfnl;
+	struct sock		*nfnl_stash;
 #endif
 #ifdef CONFIG_XFRM
 	struct netns_xfrm	xfrm;