/*
 * call-seq:
 *   easy.file_time                                   => fixnum
 *
 * Retrieve the remote time of the retrieved document (in number of
 * seconds since 1 jan 1970 in the GMT/UTC time zone). If you get -1,
 * it can be because of many reasons (unknown, the server hides it
 * or the server doesn't support the command that tells document time
 * etc) and the time of the document is unknown.
 *
 * Note that you must tell the server to collect this information
 * before the transfer is made, by setting +fetch_file_time?+ to true,
 * or you will unconditionally get a -1 back.
 *
 * This requires libcurl 7.5 or higher - otherwise -1 is unconditionally
 * returned.
 */
static VALUE ruby_curl_easy_file_time_get(VALUE self) {