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 void pdo_stmt_iter_move_forwards(zend_object_iterator *iter TSRMLS_DC)
{
	struct php_pdo_iterator *I = (struct php_pdo_iterator*)iter->data;

	if (I->fetch_ahead) {
		zval_ptr_dtor(&I->fetch_ahead);
		I->fetch_ahead = NULL;
	}

	MAKE_STD_ZVAL(I->fetch_ahead);

	if (!do_fetch(I->stmt, TRUE, I->fetch_ahead, PDO_FETCH_USE_DEFAULT,
			PDO_FETCH_ORI_NEXT, 0, 0 TSRMLS_CC)) {
		pdo_stmt_t *stmt = I->stmt; /* for PDO_HANDLE_STMT_ERR() */

		PDO_HANDLE_STMT_ERR();
		I->key = (ulong)-1;
		FREE_ZVAL(I->fetch_ahead);
		I->fetch_ahead = NULL;

		return;
	}

	I->key++;
}

static void pdo_stmt_iter_move_forwards(zend_object_iterator *iter TSRMLS_DC)
{
	struct php_pdo_iterator *I = (struct php_pdo_iterator*)iter->data;

	if (I->fetch_ahead) {
		zval_ptr_dtor(&I->fetch_ahead);
		I->fetch_ahead = NULL;
	}

	MAKE_STD_ZVAL(I->fetch_ahead);

	if (!do_fetch(I->stmt, TRUE, I->fetch_ahead, PDO_FETCH_USE_DEFAULT,
			PDO_FETCH_ORI_NEXT, 0, 0 TSRMLS_CC)) {
		pdo_stmt_t *stmt = I->stmt; /* for PDO_HANDLE_STMT_ERR() */

		PDO_HANDLE_STMT_ERR();
		I->key = (ulong)-1;
		FREE_ZVAL(I->fetch_ahead);
		I->fetch_ahead = NULL;

		return;
	}

	I->key++;
}
