/*
 * call-seq:
 *   easy.primary_ip                                  => "xx.xx.xx.xx" or nil
 *
 *   Retrieve the resolved IP of the most recent connection
 *   done with this curl handle. This string may be  IPv6 if
 *   that's enabled. This feature requires curl 7.19.x and above
 */
static VALUE ruby_curl_easy_primary_ip_get(VALUE self) {