vtls: compare and clone ssl configs properly

Compare these settings in Curl_ssl_config_matches():
- verifystatus (CURLOPT_SSL_VERIFYSTATUS)
- random_file (CURLOPT_RANDOM_FILE)
- egdsocket (CURLOPT_EGDSOCKET)

Also copy the setting "verifystatus" in Curl_clone_primary_ssl_config(),
and copy the setting "sessionid" unconditionally.

This means that reusing connections that are secured with a client
certificate is now possible, and the statement "TLS session resumption
is disabled when a client certificate is used" in the old advisory at
https://curl.haxx.se/docs/adv_20170419.html is obsolete.

Reviewed-by: Daniel Stenberg

Closes #1917