Description:
------------
http://php.net/manual/en/mysqli.get-warnings.php

can't use mysqli::get_warnings with multi queries reliably as it will get either 
segfault or empty result.

the code is supposed to print 2 times warning:
"Warning: 1050: Table 'a' already exists"
"Warning: 1050: Table 'a' already exists"

but instead it segfaults (PHP 5.3.5).

also if i run queries where only one warning is printed. it will not segfault. 
segfault seems to happen in ->next() call.

seems is because internally this is implemented as "SHOW WARNINGS" query [1]

[1] http://svn.php.net/viewvc/php/php-
src/branches/PHP_5_3/ext/mysqli/mysqli_warning.c?annotate=306939#l76

segfault must be fixed, but regarding the usage, perhaps document that you can't 
use it sanely with multi queries, due limitations of mysql protocol, as seems it 
is problem in mysql protocol, that it returns warnings only from last of the 
multi query

Test script:
---------------
<?php
$dbh = new mysqli(null, null, null, "test");
if ($dbh->connect_error) {
        die('Connect Error (' . $dbh->connect_errno . ') ' . $dbh->connect_error);
}

$create = "create temporary table if not exists a (a int4)";
$query = "$create;$create";$create;";
if ($dbh->multi_query($query)) {
        do {
                $sth = $dbh->store_result();

                if ($dbh->warning_count) {
                        $e = $dbh->get_warnings();
                        do {
                                echo "Warning: $e->errno: $e->message\n"; 
                        } while ($e->next()); 
                }
        } while ($dbh->next_result());
}
?>