[IPV4,IPV6]: Share cork.rt between IPv4 and IPv6.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index b6db16d..a42cd63 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -136,7 +136,7 @@
 		unsigned int		flags;
 		unsigned int		fragsize;
 		struct ip_options	*opt;
-		struct rtable		*rt;
+		struct dst_entry	*dst;
 		int			length; /* Total length of all frames */
 		__be32			addr;
 		struct flowi		fl;