nmbd_incomingdgrams.c: Fix bug with Syntax 5.1 servers reported by SGI where

nmbd_incomingdgrams.c: Fix bug with Syntax 5.1 servers reported by SGI where
they do host announcements to LOCAL_MASTER_BROWSER_NAME<00> rather than
WORKGROUP<1d>.
nmbd_incomingrequests.c: Deal with WINS_PROXY_NAME issues - don't reply
with that name if it's the same broadcast net.
nmbd_serverlistdb.c: Stopped writing "Unknown" for local master browsers
we don't know.
nmbd_winsproxy.c: Deal with WINS_PROXY_NAME issues - don't reply
with that name if it's the same broadcast net.
Jeremy.
(This used to be commit 5adfff94c9020bd57f84ccbc8fba5b1d8d1615af)