Description:
------------
PHP shutdown handlers (registered via register_shutdown_function) are not tracked for request_terminate_timeout. 

This bug is related to bug #78413 due to the same underlying reasons. Request processing loop in fpm_main.c does this sequence of calls:
  while () {
     <get request>
     ...
     php_execute_script()
     ...
     fpm_request_end()  -> sets request stage to FPM_REQUEST_FINISHED
     ...
     php_request_shutdown() --> calls shutdown handlers
  }

and since request_termination_timeout is applied only to ((stage > FPM_REQUEST_ACCEPTING) && (stage < FPM_REQUEST_END)) it is effectively ignored.

This creates an opportunity for PHP code to seize control of worker process for an arbitrary amount of time.

Test script:
---------------
<?php

function func() {
    sleep(100000);
}

register_shutdown_function('func');


Expected result:
----------------
Php worker being terminated by fpm after %request_terminate_timeout% of execution time