We destroy classes of dl()'ed modules in clean_module_classes(), during
shutdown. Child classes of a module use structures of the parent class (such as
inherited properties), which are destroyed earlier, so we have a use-after-free
when destroying a child class.
Here I destroy classes in reverse order, as it is done in zend_shutdown() for
persistent classes.
Fixes GH-17961
Fixes GH-15367
When observer is enabled, we normally add an extra temporary to all
functions, to store the previously observed frame. However, this is done in
zend_observer_post_startup() so it doesn't happen to dl'ed() functions.
One possible fix would be to move that from zend_observer_post_startup()
to zend_register_functions(), but this would be too early: Observer may
not be enabled when zend_register_functions() is called, and may still be
enabled later.
However, when zend_register_functions() is called at run-time (during dl()),
we know definitively whether observer is enabled.
Here I update zend_register_functions() to add a temporary to dl'ed()
functions when observer is enabled.
Fixes: GH-17211
Closes: GH-17220
