Description:
------------
Segmentation fault in function imap_open if script opens
~ 4000 files before.
I have increased __FD_SETSIZE in
/usr/include/bits/typesizes.h
/usr/include/linux/posix_types.h
to 262144 before compiling php (4.4.4, 5.1.6, 4.4.5-dev)


Reproduce code:
---------------
<?                                                                                                              
                                                                                                                
    $basedir = "/tmp/php_testcase";                                                                             
                                                                                                                
    if (! file_exists ($basedir)) {                                                                             
        mkdir ($basedir, 0700);                                                                                 
    }                                                                                                           
                                                                                                                
    $fds = array();                                                                                             
    for ($i = 0; $i < 4096; $i++) {                                                                             
        $fds[] = fopen ($basedir . '/file_' . $i, 'w');                                                         
    }                                                                                                           
                                                                                                                
    imap_open ('{127.0.0.1:143/imap/notls}INBOX',                                                               
               'test@test.com', 'test', 64);                                                                    
                                                                                                                
?>

Expected result:
----------------
no segfault

Actual result:
--------------
Segmentation fault.