Named was stopping nameserver address resolution attempts too soon
when dual stack servers are configured. Dual stack servers are
used when there are *not* addresses for the server in a particular
address family so find->status == DNS_ADB_NOMOREADDRESSES is not a
sufficient stopping condition when dual stack servers are available.
Call fctx_try to see if the alternate servers can be used.
(cherry picked from commit f98a8331aa)
14bd113b8f