func_curl.c: Add additional CURL options for SSL requests

func_curl.c: Add additional CURL options for SSL requests

This patch adds additional CURL TLS options / options to support mTLS authenticated requests:

* ssl_verifyhost - perform a host verification on the peer certificate (CURLOPT_SSL_VERIFYHOST)
* ssl_cainfo - define a CA certificate file (CURLOPT_CAINFO)
* ssl_capath - define a CA certificate directory (CURLOPT_CAPATH)
* ssl_cert - define a client certificate for the request (CURLOPT_SSLCERT)
* ssl_certtype - specify the client certificate type (CURLOPT_SSLCERTTYPE)
* ssl_key - define a client private key for the request (CURLOPT_SSLKEY)
* ssl_keytype - specify the client private key type (CURLOPT_SSLKEYTYPE)
* ssl_keypasswd - set a password for the private key, if required (CURLOPT_KEYPASSWD)

UserNote: The following new configuration options are now available
in the res_curl.conf file, and the CURL() function: 'ssl_verifyhost'
(CURLOPT_SSL_VERIFYHOST), 'ssl_cainfo' (CURLOPT_CAINFO), 'ssl_capath'
(CURLOPT_CAPATH), 'ssl_cert' (CURLOPT_SSLCERT), 'ssl_certtype'
(CURLOPT_SSLCERTTYPE), 'ssl_key' (CURLOPT_SSLKEY), 'ssl_keytype',
(CURLOPT_SSLKEYTYPE) and 'ssl_keypasswd' (CURLOPT_KEYPASSWD). See the
libcurl documentation for more details.