Description:
------------
Sorry for that english :D

When trying to use the multi_query functions from mysqli adapter, it always fails with an syntax error if more than one sql statement is given to the function/object.

Reproduce code:
---------------
$mysqli = new mysqli('localhost', 'root', '', 'test');

$query  = "SELECT CURRENT_USER();";
$query .= "SELECT CURRENT_USER();";

if ($mysqli->multi_query($query)) {
   do {
       	if ($result = $mysqli->store_result()) {
           while ($row = $result->fetch_row()) {
               printf("%s\n", $row[0]);
           }
           $result->close();
       	}
   } while ($mysqli->next_result());
} else {
	echo $mysqli->error;
}

$mysqli->close();

Expected result:
----------------
root@localhost
root@localhost

Actual result:
--------------
Fehler in der Syntax bei ';SELECT CURRENT_USER()' in Zeile 1.

(German Locale)