[erlang-patches] Add missing HAVE_IN6 && AF_INET6 ifdef

[Peer Stritzinger]

Hi,

Please fetch:

  git fetch git@REDACTED:peerst/otp.git inet6_less_build_fix

Add missing HAVE_IN6 && AF_INET6 ifdef

This prevents building for operating systems that do not yet have IPv6
compatible socket API. Error can be reproduced by (cross)building for
a os that doesn't have these headers. This will abort with a error
about incomplete type 'struct in6_addr'. All other uses of IPv6 API in
inet_drv.c are conditionalized like in the patch.

https://github.com/peerst/otp/compare/inet6_less_build_fix
https://github.com/peerst/otp/compare/inet6_less_build_fix.patch

Cheers,
Peer Stritzinger