[NET] Generalise tcp_listen_opt

This chunks out the accept_queue and tcp_listen_opt code and moves
them to net/core/request_sock.c and include/net/request_sock.h, to
make it useful for other transport protocols, DCCP being the first one
to use it.

Next patches will rename tcp_listen_opt to accept_sock and remove the
inline tcp functions that just call a reqsk_queue_ function.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
index 6727780..c3328fa 100644
--- a/net/ipv4/tcp_diag.c
+++ b/net/ipv4/tcp_diag.c
@@ -529,9 +529,9 @@
 
 	entry.family = sk->sk_family;
 
-	read_lock_bh(&tp->syn_wait_lock);
+	read_lock_bh(&tp->accept_queue.syn_wait_lock);
 
-	lopt = tp->listen_opt;
+	lopt = tp->accept_queue.listen_opt;
 	if (!lopt || !lopt->qlen)
 		goto out;
 
@@ -588,7 +588,7 @@
 	}
 
 out:
-	read_unlock_bh(&tp->syn_wait_lock);
+	read_unlock_bh(&tp->accept_queue.syn_wait_lock);
 
 	return err;
 }