Description:
------------
I think, the bug #29656 (closed for 5.0.1) persists in 5.1.2

Segfault when trying to access 
$result->num_rows
after calling $result->close() method

Reproduce code:
---------------
<?php
$mysqli = new mysqli('localhost','user','pass','db');
$result = $mysqli->query('select 1');

$result->close();
echo $result->num_rows;

$mysqli->close();

?>

Expected result:
----------------
1

Actual result:
--------------
segmentation fault

I can post backtrace a bit later when recompile PHP with debugging if required.