Returns an associative array with the following elements:
| version_number | cURL 24 bit version number |
| version | cURL version number, as a string |
| ssl_version_number | OpenSSL 24 bit version number |
| ssl_version | OpenSSL version number, as a string |
| libz_version | zlib version number, as a string |
| host | Information about the host where cURL was built |
| age | |
| features | A bitmask of the CURL_VERSION_XXX constants |
| protocols | An array of protocols names supported by cURL |