Add a nexthop6 config option.

Will be used to set the NEXT_HOP for IPv6 routes, otherwise our address in
ipv6_prefix is used as the next hop.

Signed-off-by: Benjamin Cama <benoar@dolka.fr>

l2tpns.h

@@ -724,6 +724,7 @@ typedef struct
 		int keepalive;
 		int hold;
 	} neighbour[BGP_NUM_PEERS];
+	struct in6_addr	nexthop6_address;
 #endif
 } configt;