Case statement in where condition is removed by magic parameters

For some reason, the case statement is removed from a where condition.

```
SELECT a FROM users u WHERE status = (CASE WHEN u.id = 1 THEN u.status_1 ELSE u.status_2 END)

=>

SELECT a FROM users u
```

This is a failing test showcasing the issue.

Author: moufmouf

tests/Mouf/Database/MagicQueryTest.php

@@ -177,6 +177,9 @@ public function testStandardSelect()
 
         $sql = 'SELECT a FROM users u, users u2';
         $this->assertEquals('SELECT a FROM users AS u CROSS JOIN users AS u2', self::simplifySql($magicQuery->build($sql)));
+
+        $sql = 'SELECT a FROM users u WHERE status = (CASE WHEN u.id = 1 THEN u.status_1 ELSE u.status_2 END)';
+        $this->assertEquals('foo', self::simplifySql($magicQuery->build($sql)));
     }
 
     /**