Description:
------------
The php-mssql extension implements the nextRowset feature to advance to the next result set from a query.  the current PDO_DBLIB does not provide this functionality.


Reproduce code:
---------------
$db = new PDO("dblib:host=host:1433;dbname=tempdb","user","pass");

$sql = <<<EOSQL
SELECT 1;
SELECT 2;
SELECT 3;
EOSQL;

$res = $db->prepare($sql);
$res->execute();

$row = $res->fetch(PDO::FETCH_NUM);

while ($row = $res->fetch(PDO::FETCH_NUM)
    || ($res->nextRowset() && $row = $res->fetch(PDO::FETCH_NUM))) {
  echo $res->columnCount().':';
  echo implode(',',$row)."\n";
}


Expected result:
----------------
1:1
1:2
1:3

Actual result:
--------------
PDOStatement::nextRowset(): SQLSTATE[IM001]: Driver does not support this function: driver does not support multiple rowsets in nextresult-pdo.php on line 34