This is often bundled with ruby, but not always.

No more warnings, yay.

macos is disabled for now, as it's crashy, as per patch trigger.

LibreSSL uses a mostly OpenSSL 1.0.1 compatible API, with the
alarmingly notable exception of the version API. When the library is
loaded on macOS with LibreSSL the verison check introduced in lian#42 the
gem was incompatible with LibreSSL.

This change may not be ideally forward-compatible if APIs change and
may need a new strategy eventually, but is not noticeably weaker than
the version based strategy. It is notably functional on both macOS
with LibreSSL 2.8.3, as well as remaining compatible with OpenSSL
1.1.1f on Ubuntu.

On macOS the library load is handled in a specific and incompatible
way, which is handled by the extension. As the gem uses the extension
elsewhere, taking a direct dependency on that, and looking up symbols
from in-process should be safe and sufficient.