Patch to ignore service principals when accepting connexions.

[Sam Hartman]

I definitely agree that the forward/reverse resolution creates issues
for acquire_cred.  There's a kind of annoying Debian bug open on this
where the name you end up with depends on whether you have A records or
just AAAA records.  Also, as you point out it is a source of failure.

So, I would like to express support for a configuration knob to ignore
the hostname and to look into what we can do about acceptor-side use of
DNS.