vxlan: add ipv6 route short circuit support

route short circuit only has IPv4 part, this patch adds
the IPv6 part. nd_tbl will be needed.

Cc: David S. Miller <davem@davemloft.net>
Cc: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 5339cab..bcf9573 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -153,6 +153,7 @@
 	int (*ipv6_dst_lookup)(struct sock *sk, struct dst_entry **dst,
 				struct flowi6 *fl6);
 	void (*udpv6_encap_enable)(void);
+	struct neigh_table *nd_tbl;
 };
 extern const struct ipv6_stub *ipv6_stub __read_mostly;