s4:nbt_server: simulate nmbd and provide unexpected handling

s4:nbt_server: simulate nmbd and provide unexpected handling

This is needed in order to let nbt_getdc() work against
another AD DC and get back a modern response with
DNS based names. Instead of falling back to
the ugly name_status_find() that simulates just
an NETLOGON_SAM_LOGON_RESPONSE_NT40 response.

This way dsgetdcname() can work with just the netbios
domain name given and still return an active directory
response.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15620

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>