In bpo-1635741, many C extension modules are converted to PEP 489 multiphase initialization and/or modified to get a module state. Problem: the module state cannot be accessed in some functions, and so some of these changes had to workaround the fact that PEP 573 "Module State Access from C Extension Methods" is not implemented yet.

This issue tracks C extension modules which should be modified once PEP 573 will be implemented:

* _functools: Py_CLEAR(kwd_mark); is commented in _functools_free()
  See commit eacc07439591c97f69ab4a3d17391b009cd78ae2

* _abc: abc_invalidation_counter is shared by all module instances. abc_data_new() requires access to abc_invalidation_counter but it doesn't have access to the module state. abc_invalidation_counter should be moved to the module state.