Make MDNSResponder STFU.  There are simply far too many log messages it likes
to emit in a wide variety of circumstances, none of which can be meaningfully
parsed by the user (or, frankly, even by us) and even if it failed to work
entirely, the failure mode would be fairly benign (no advertisements) so simply
making it shut up won't end the world if it falls over on a user's machine and
stops working completely (a situation we'd be unlikely to understand or fix
anyway, so this is sort of a case of "never log an error message you don't know
how to can't handle" as well).

Ticket #: 4154