network wildcard entries doesn't work on multiple zones

[m-emerson]

If I have multiple zones with the networks set as ["*"], the net filter only adds the first zone with the wildcard entry to nic.zones, which means the other zones don't get updated.

See: https://github.com/joyent/triton-cns/blob/master/lib/net-filter.js#L75

Can reproduce by adding several zones that all have networks set as "[*]".