Preferred way of passing user context void* inside SSL*

[Salz, Rich]

>    Is there a way for me to piggyback a void* inside the SSL structure so
    that I can access it from within the callback?
  
Yes, you can use SSL_set_app_data and SSL_get_app_data which are documented in https://github.com/openssl/openssl/pull/10216 (and due to be merged to master soon)