[php-src] Issue #8723: Cannot switch fibers in destructor.

Issue: https://github.com/php/php-src/issues/8723 Author: bartvanhoutte ### Description 👋 I've noticed some unexpected behaviour with Fibers while working with ReactPHP that seem to boil down to not being able to switch Fibers in a destructor. ```php <?php $foo = new class { public function __destruct() { $fiber = new Fiber(function () { Fiber::suspend(42); }); var_dump($fiber->start()); } }; unset($foo); ``` Resulted in this output: ``` /usr/bin/php /home/bart/uv/destructor.php PHP Fatal error: Uncaught FiberError: Cannot switch fibers in current execution context in /home/bart/uv/destructor.php:11 Stack trace: #0 /home/bart/uv/destructor.php(11): Fiber->start() #1 /home/bart/uv/destructor.php(15): class@anonymous->__destruct() #2 {main} thrown in /home/bart/uv/destructor.php on line 11 Process finished with exit code 255 ``` But I expected this output instead: ``` int(42) ``` ### PHP Version PHP 8.1.6 ### Operating System Ubuntu 20.04