Increase refcount of zval, not zend_object
Increase refcount of zval, not zend_object

Fix #289

sjinks/PHP-CPP,sjinks/PHP-CPP,CopernicaMarketingSoftware/PHP-CPP,dreamsxin/PHP-CPP,sjinks/PHP-CPP,CopernicaMarketingSoftware/PHP-CPP,dreamsxin/PHP-CPP,sjinks/PHP-CPP