zclient: fix router-id calculation for IPv6 (#595)

If router-id is not specified in ospf6d.conf, ospf6d will get it from
the zebra daemon. But ospf6d originates Link LSAs before the router-id
is returned by zebra, thus this router's Link LSAs will be flooded
with AdvRouter set to 0.

* zclient.c: zclient_start(): send ZEBRA_INTERFACE_ADD message after
  ZEBRA_ROUTER_ID_ADD, not before
1 file changed