r10491: First step towards wbinfo -t: This issues a name request for the primary

r10491: First step towards wbinfo -t: This issues a name request for the primary
domain and gets the DC's name via a mailslot call.

Metze, I renamed wbsrv_queue_reply to wbsrv_send_reply in accordance with
irpc_send_reply. Having _queue_ here and _send_ there is a bit confusing. And
as everything is async anyway, the semantics should not be too much of a
problem.

Volker
(This used to be commit 4637964b19c6e9f7d201b287e2d409d029fced01)