Description:
------------
After compiling and installing PHP 5.2.10, the dblib PDO driver has appeared to stop connecting. This bug has also been documented in bug #48539 for PHP 5.3.0RC4

Reproduce code:
---------------
try {
    $hostname = 'sql.example.com';
    $port     = 1433;
    $dbname   = 'dbname';
    $username = 'username';
    $password = 'password';
    $dsn      = sprintf('dblib:host=%s:%d;dbname=%s', $hostname, $port, $dbname);

    $dbh = new PDO ($dsn, $username, $password);
    
    echo 'Yippie!';
    
} catch (PDOException $e) {
    echo $e->getMessage();
}


Expected result:
----------------
Yippie

Actual result:
--------------
SQLSTATE[] (null) (severity 0)