message: fix serialize test20
diff: --TEST--
  -swoole_serialize: Object test, __wakeup
  +swoole_serialize: Object test, stdclass
  --SKIPIF--
  <?php
  require __DIR__ . "/../include/skipif.inc";
  @@ -10,13 +10,15 @@ if (!class_exists("swoole_serialize", false))
  ?>
  --FILE--
  <?php
  +ini_set("display_errors", "Off");
  function test($variable, $test) {
  - $unserialized = swoole_serialize::unpack($variable, UNSERIALIZE_OBJECT_TO_STDCLASS);
  + $serialized = swoole_serialize::pack($variable);
  + $unserialized = swoole_serialize::unpack($serialized, UNSERIALIZE_OBJECT_TO_STDCLASS);
  echo UNSERIALIZE_OBJECT_TO_STDCLASS, PHP_EOL;
  var_dump($unserialized);
  - echo $test || get_class($unserialized) == "stdClass" ? 'OK' : 'ERROR' || get_class($unserialized->sub) == "stdClass" ? 'OK' : 'ERROR', PHP_EOL;
  + echo get_class($unserialized->sub) == "stdClass" ? 'OK' : 'ERROR', PHP_EOL;
  }
  class Obj {
  @@ -33,11 +35,12 @@ $o->sub = new subObj();
  test($o, true);
  ?>
  --EXPECTF--
  -object
  -object(Obj)#%d (2) {
  - ["a"]=>
  - int(1)
  +2
  +object(stdClass)#4 (1) {
  + ["sub"]=>
  + object(stdClass)#3 (1) {
  ["b"]=>
  - int(3)
  + string(3) "sub"
  + }
  }
  OK
  