Handler passed to ssl_options::set_error_handler not invoked

[Thiesius]

In the same code as referenced in #337 the callback is not called, when SSL_CTX_load_verify_locations inside paho-mqtt-c SSLSocket.c fails (when an empty string is passed as caPath). I didn't investigate this issue any further so I can't tell if the issue is in the underlying C library or the C++ wrapper.

[fpagliughi]

Do you have a small sample that demonstrates the failure that you're seeing?

[fpagliughi]

Closing due to inactivity and an inability to reproduce without additional information.