Add ssl_cry() function to display error message plus any detailed error messages that OpenSSL might care to provide.
This can help to debug SSL communication issues.

Example output with a couple of problematic SSL client sessions (new log messages start with "-->" to indicate that they are providing additional detail to a previous log message):

Mongoose "2.9, $Rev: 517 $" started on port(s) "80,443s", serving directory "."
[1274991792] [error] [client 10.50.50.50] worker_thread: SSL handshake error
[1274991792] [error] [client 10.50.50.50]   --> error:1408F10B:SSL routines:SSL3_GET_RECORD:wrong version number
[1274991882] [error] [client 10.50.50.50] worker_thread: SSL handshake error
[1274991882] [error] [client 10.50.50.50]   --> error:1408A0C1:SSL routines:SSL3_GET_CLIENT_HELLO:no shared cipher