netfilter: make /proc/net/netfilter pernet

This patch makes this proc dentry pernet. So far only init_net
had a /proc/net/netfilter directory.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index de644bc..b176978 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -17,6 +17,7 @@
 #include <net/netns/ipv6.h>
 #include <net/netns/sctp.h>
 #include <net/netns/dccp.h>
+#include <net/netns/netfilter.h>
 #include <net/netns/x_tables.h>
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 #include <net/netns/conntrack.h>
@@ -94,6 +95,7 @@
 	struct netns_dccp	dccp;
 #endif
 #ifdef CONFIG_NETFILTER
+	struct netns_nf		nf;
 	struct netns_xt		xt;
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 	struct netns_ct		ct;