crypto: freelist_max_len is gone in OpenSSL 1.1.0

The freelist_max_len member of SSL* (and the freelist itself) has been
removed in OpenSSL 1.1.0. Thus this change will be necessary at some
point but, for now, it makes it a little easier to build with 1.1.0
without breaking anything for previous versions of OpenSSL.

PR-URL: https://github.com/nodejs/node/pull/10859


Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Shigeki Ohtsu <ohtsu@ohtsu.org>