/*
 * call-seq:
 *   easy.redirect_url                               => "http://some.url" or nil
 *
 * Retrieve  the URL a redirect would take you to if you 
 * would enable CURLOPT_FOLLOWLOCATION.
 *
 * Requires libcurl 7.18.2 or higher, otherwise -1 is always returned.
 */
static VALUE ruby_curl_easy_redirect_url_get(VALUE self) {