Encode domain names before passing them on to the libc resolver.
Some getaddrinfo() implementations support IDNA 2008, some only
IDNA 2003 and some don't support i18n domain names at all.
This is a potential security issue because it means a domain name
might resolve differently depending on the system that libuv is
running on.
Fixes: https://github.com/libuv/libuv/issues/2028
PR-URL: https://github.com/libuv/libuv/pull/2046
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
