Description:
------------
Function shmop_open increases memory used by Apache with about 4KB every time it is invoked, and doesn't free it. It looks like memory allocated for php_shmop struct is not freed.

Reproduce code:
---------------
<?
$shmid = shmop_open(0xff2, "c", 0644, 8);
shmop_close($shmid);
?>

Expected result:
----------------
Memory used by apache should be increased only once, when shared memory segment is created. Refreshing the page should not increase used memory or it must free it when script ends.

Actual result:
--------------
Every time the script is executed additional 4KB are added to the memory used by Apache.