refresh requests to WINS when not registered

[Andrew Tridgell]

This is primarily for Jeremy, but I thought others might be
interested.

When a Samba WINS server is restarted it needs to be able to recover
its name list within a reasonable period of time. If it can load the
list from wins.dat then all is OK but it is also important to be able
to recover when wins.dat is unavailable for some reason.

I just tested at home and found that when nmbd is restarted without
wins.dat it does not recover its name list at all. The problem is that
when the various machines send their name refresh requests nmbd sends
error replies and does not add the names. This is actually correct
behaviour but unfortunately NTWS4 does not then respond by
re-registering its names. 

I think we need to handle this errant NT behaviour by treating name
refresh requests on unregistered names just like name registration
requests. Is there any reason why we shouldn't do this?