Remove some XXXX commens in dns.c

Previously, I was freaking out about passing an unspec address to
dns_found_answer() on an error, since I was using the address type to
determine whether the error was an error on an ipv4 address lookup or
on an ipv6 address lookup.  But now dns_found_answer() has a separate
orig_query_type argument to tell what kind of query it is, so there's
no need to freak out.