fix: recive ctrl+c signal kill child process

[alberthuang24]

If the abnormal main process exits abnormally before the repair, the child process will remain.

$wp=new \QXS\WorkerPool\WorkerPool();
            $wp->setWorkerPoolSize(8)
               ->create(new \QXS\WorkerPool\ClosureWorker(
                function($input, $semaphore, $storage) {
                    usleep(5000);
                    echo $input;
                }
                }
));

for ($i = 0; $i < 20; $i ++) {
$wp->run($i);
}

$wp->waitForAllWorkers();
$wp->destroy();

run php ./test.php and ctrl+c keydown;

[qxsch]

Thanks a lot for your contribution