getaddrinfo - conditionally compile 

Ah, ok. It is not v6 per-say, but the RFC 2553 advanced socket-api stuff this is the issue.

So, a quick google leads me to believe there are a few reasonable paths forward:

* See if early adoption of IPv6 cygwin code is reasonable:

http://win6.jp/Cygwin/index.html

* Pull over another getaddrinfo implementation and conditionally compile for environments that don't have getaddrinfo. (autoconf pain.)
    - gnulib (lots here - probably too much and I'm not crazy about license)
    - http://www.sra.co.jp/people/m-kasahr/getaddrinfo/ (needs testing)
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Autoconf: Update AC_CHECK_HEADERS (see bwctl)
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