/*
 * call-seq:
 *   easy.http_post("url=encoded%20form%20data;and=so%20on") => true
 *   easy.http_post("url=encoded%20form%20data", "and=so%20on", ...) => true
 *   easy.http_post("url=encoded%20form%20data", Curl::PostField, "and=so%20on", ...) => true
 *   easy.http_post(Curl::PostField, Curl::PostField ..., Curl::PostField) => true
 *
 * POST the specified formdata to the currently configured URL using
 * the current options set for this Curl::Easy instance. This method
 * always returns true, or raises an exception (defined under
 * Curl::Err) on error.
 *
 * The Content-type of the POST is determined by the current setting
 * of multipart_form_post? , according to the following rules:
 * * When false (the default): the form will be POSTed with a
 *   content-type of 'application/x-www-form-urlencoded', and any of the
 *   four calling forms may be used.
 * * When true: the form will be POSTed with a content-type of
 *   'multipart/formdata'. Only the last calling form may be used,
 *   i.e. only PostField instances may be POSTed. In this mode,
 *   individual fields' content-types are recognised, and file upload
 *   fields are supported.
 *
 */
static VALUE ruby_curl_easy_perform_post(int argc, VALUE *argv, VALUE self) {