bug1160877: loopback addresses are not ignored when the AI_ADDRCONFIG
flag is set.
(https://bugs.launchpad.net/tarantool/+bug/1160877)

getaddrinfo("::1") may fail if machine has no public ipv6 addresses due
to AI_ADDRCONFIG behaviour.
Minor edit of a comment.
Merge branch 'master' into coio-fiber-detach
coio-fiber-detach: review fixes.