/*
 * call-seq:
 *   easy.ssl_version = value                         => fixnum or nil
 *
 * Sets the version of SSL/TLS that libcurl will attempt to use. Valid
 * options are Curl::CURL_SSLVERSION_TLSv1, Curl::CURL_SSLVERSION::SSLv2,
 * Curl::CURL_SSLVERSION_SSLv3 and Curl::CURL_SSLVERSION_DEFAULT
 */
static VALUE ruby_curl_easy_ssl_version_set(VALUE self, VALUE ssl_version) {