IPv6 transport-ready resolvers/DNS servers. Need careful configuration
when enable it. (default config is not affected).
See manpage for details.
XXX visible symbol __res_opt() is added, however, it is not supposed to be
called from outside, libc minor is not bumped.
Obtained from: KAME/NetBSD
since it has far wider impact than hostname lookups (including passwords).
Note that this has more ugly symbol hiding and binary compatability hacks
that can go away the second we bump majors.
Obtained from: Mostly from diff against ISC bind-8.1.2 sources