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.c

@@ -157,6 +157,7 @@ config_descriptt config_values[] = {
 	CONFIG("cluster_hb_timeout", cluster_hb_timeout, INT),
  	CONFIG("cluster_master_min_adv", cluster_master_min_adv, INT),
 	CONFIG("ipv6_prefix", ipv6_prefix, IPv6),
+	CONFIG("nexthop6_address", nexthop6_address, IPv6),
 	{ NULL, 0, 0, 0 },
 };