[IPV6]: Generalise the tcp_v6_lookup routines

In the same way as was done with the v4 counterparts, this will be moved
to inet6_hashtables.c.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ipv6.h

@@ -193,6 +193,11 @@ struct inet6_skb_parm {
 
 #define IP6CB(skb)	((struct inet6_skb_parm*)((skb)->cb))
 
+static inline int inet6_iif(const struct sk_buff *skb)
+{
+	return IP6CB(skb)->iif;
+}
+
 struct tcp6_request_sock {
 	struct tcp_request_sock	req;
 	struct in6_addr		loc_addr;