facebook/hhvm — pull request #1459 by javer (2013-12-29 23:00:40+00:00)
Title: Fix memory leak in pdo_parse_params

Fixed memory leak after executing PDOStatement::execute() with bound parameters. Also removed unnecessary copying of result query string.

Test case (I don't know whether it can be tested in Travis because it requires MySQL connection):
```php
prepare('SELECT :data = 1');
$stmt->bindValue(':data', $data);
$stmt->execute();
$stmt = null;
echo sprintf("%dM\n", memory_get_usage(true) / 1048576);
}
```