#70 sys-gethostbyname and TRY_AGAIN

[Shiro Kawai]

Add option(s) to sys-gethostbyname so that it can raise an error only faiilure and it can retry on TRY_AGAIN. Similar change can be possible on sys-getaddrinfo.

https://sourceforge.net/mailarchive/message.php?msg_id=30033548