r19249: Attempt to fix a site lookup bug found by Guenther.

r19249: Attempt to fix a site lookup bug found by Guenther.

- "The problem is, with a fresh system, we don't know our sitename,
therefor we do a stupid DNS query for all DCs. The reply we get is a
round-robin list of all 21 DCs, we just pick the first, contact that
and safe that INET.COM#1C query in the name cache for later use...
What we need to do if we don't yet know our sitename, is to contact to
any DC, get the CLDAP reply to tell us in which site we are, then flush
the namecache and requery DNS including the sitename"

Implement the flushing of the #1C entries for a given NetBIOS name/realm
when looking up the site value.

Jeremy.
(This used to be commit b2d1e44f59d32c91b1d48eacd1a158ba7b65762d)