Add clean_module_functions()

[twose]

Add clean_module_functions() to clean functions which are registered by zend_register_functions().
The general logic of clean_module_functions() is consistent with clean_module_classes().

[twose]

Here we need dl() an extension that uses zend_register_functions() directly.
I can't think of any low-cost testing way for the time being...

[arnaud-lb]

You can use the dl_test extension for testing this. You can add some zend_register_function() calls if needed.

[twose]

You can use the dl_test extension for testing this. You can add some zend_register_function() calls if needed.

@arnaud-lb Thank you for pointing this out!

Here is the test results:

[arnaud-lb]

Thank you @twose !

I've just added a comment and moved the test to ext/standard/general_functions because this is the other dl() tests are (ext/dl_test/tests is for testing the extension itself)