Use AI_ADDRCONFIG for more efficient getaddrinfo

Use AI_ADDRCONFIG for more efficient getaddrinfo

Add AI_ADDRCONFIG to the hint flags for every invocation of
getaddrinfo which wasn't already using it.  This is often the default
behavior when no hints are specified, but we tend to specify hints a
lot, so we have to say it ourselves.  AI_ADDRCONFIG causes AAAA
lookups to be skipped if the system has no public IPv6 interface
addresses, usually saving a couple of DNS queries per getaddrinfo
call and allowing DNS caching to be much more effective without the
need for negative caching.

ticket: 6923

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24978 dc483132-0cff-0310-8789-dd5450dbe970