(PHP 5, PHP 7, PHP 8)
php_user_filter::onClose — Called when closing the filter
   This method is called upon filter shutdown (typically, this is also
   during stream shutdown), and is executed after
   the flush method is called.  If any resources
   were allocated or initialized during onCreate()
   this would be the time to destroy or dispose of them.
  
У цієї функції немає параметрів.
Return value is ignored.
