Description:
------------
Ubuntu 18.04.2
MySQL 8.0.15

"ALTER VIEW" queries don't work as prepared statements if emulation is disabled.

Test script:
---------------
$pdo = new PDO('mysql:host=127.0.0.1;port=3306;dbname=database', 'user', 'password', [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_EMULATE_PREPARES => false,
]);

$pdo->prepare('create view `test` as select 1')->execute();
$pdo->prepare('alter view `test` as select 1')->execute();

Expected result:
----------------
Successful query execution.

Actual result:
--------------
The last line throws an exception:

"PDOException: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active.  Consider using PDOStatement::fetchAll().  Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute."