[UDP]: Make full use of proto.h.udp_hash innovation.

After this we have only udp_lib_get_port to get the port and two 
stubs for ipv4 and ipv6. No difference in udp and udplite except
for initialized h.udp_hash member.

I tried to find a graceful way to drop the only difference between
udp_v4_get_port and udp_v6_get_port (i.e. the rcv_saddr comparison 
routine), but adding one more callback on the struct proto didn't 
appear such :( Maybe later.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
index 21be3a8..321b81a 100644
--- a/net/ipv6/udp_impl.h
+++ b/net/ipv6/udp_impl.h
@@ -11,6 +11,8 @@
 extern void 	__udp6_lib_err(struct sk_buff *, struct inet6_skb_parm *,
 			       int , int , int , __be32 , struct hlist_head []);
 
+extern int	udp_v6_get_port(struct sock *sk, unsigned short snum);
+
 extern int	udpv6_getsockopt(struct sock *sk, int level, int optname,
 				 char __user *optval, int __user *optlen);
 extern int	udpv6_setsockopt(struct sock *sk, int level, int optname,