[NETFILTER]: add /proc/net/netfilter interface to nf_queue

This patch adds a /proc/net/netfilter/nf_queue file, similar to the
recently-added /proc/net/netfilter/nf_log.  It indicates which queue
handler is registered to which protocol family.  This is useful since
there are now multiple queue handlers in the treee (ip[6]_queue,
nfnetlink_queue).

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index ec58c4d..31a9d63 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -5,6 +5,7 @@
 #include <linux/proc_fs.h>
 #include <linux/skbuff.h>
 #include <linux/netfilter.h>
+#include <linux/seq_file.h>
 #include <net/protocol.h>
 
 #include "nf_internals.h"