Support LibreSSL
There seem to be issues when using LibreSSL as drop-in replacement for OpenSSL. See https://github.com/rockdaboot/wget2/issues/236#issuecomment-779010988
There seem to be issues when using LibreSSL as drop-in replacement for OpenSSL. See https://github.com/rockdaboot/wget2/issues/236#issuecomment-779010988