After taking into consideration the following, I think this should be
removed :

- OpenSSL isn't the default on Apple platforms
- you have to jump through hoops to get CMake to use OpenSSL on macOS
(headers aren't in `/usr/include`, so you have to provide `-DOPENSSL_*`
overrides)
- users are likely (as getting anywhere near the installed 0.9.8 version
is insanity IMHO) to package a "modern" version, which wouldn't be
marked as deprecated