Remaining tasks on resolver overhaul

[Rich Felker <dalias@libc.org>]

The vast majority of what I'd call the resolver overhaul is done now,
but a few things remain that don't have an impact on the architecture
and design, but which still might be a lot of work:

- Sorting results per RFC 3484 or at least a subset of its rules.

- AI_ADDRCONFIG -- but maybe the current implementation of it as a nop
  is actually best; see
  https://fedoraproject.org/wiki/Networking/NameResolution/ADDRCONFIG

- IDN support.

- IPv6 scope-id parsing.

- One remaining legacy resolver function: dn_comp.

- And most importantly: REVIEW AND TESTING.

We're behind schedule for the roadmap, so of the above items, the ones
I'd really like to focus on for release are those which most impact
IPv6 usability.

Since we have some resolver items remaining to work on, as well as a
lot of secondary targets that don't look like they're going to make it
for 1.1.2, I may update the roadmap to insert an extra release cycle
before the next one.

I'd like comments on what should be prioritized at this point. And of
course any bug reports/regressions associated with the recent commits.

Rich