Fix bug #73331 - do not try to serialize/unserialize objects wddx can not handle

Proper soltion would be to call serialize/unserialize and deal with the result,
but this requires more work that should be done by wddx maintainer (not me).
static int pdo_row_serialize(zval *object, unsigned char **buffer, zend_uint *buf_len, zend_serialize_data *data TSRMLS_DC)
{
	php_error_docref(NULL TSRMLS_CC, E_WARNING, "PDORow instances may not be serialized");
	return FAILURE;
}

static int pdo_row_serialize(zval *object, unsigned char **buffer, zend_uint *buf_len, zend_serialize_data *data TSRMLS_DC)
{
	php_error_docref(NULL TSRMLS_CC, E_WARNING, "PDORow instances may not be serialized");
	return FAILURE;
}
