Fix is_myname_or_ipaddr() to be robust against strange DNS setups.

Fix is_myname_or_ipaddr() to be robust against strange DNS setups.

If IPv6 DNS names are turned on, but Samba isn't configured to
listen on an IPv6 interface, then is_myname_or_ipaddr() can return
false on a valid DNS name that it should detect is our own. If the
IPv6 addr is returned by preference, then looking at the first addr
only causes is_myname_or_ipaddr() to fail. We need to look at all the
addresses returned by the DNS lookup and check all of them against
our interface list. This is an order N^2 lookup, but there shouldn't
be enough addresses to make this a practical problem.

Jeremy.