[Cython] Control Flow

I've recently fixed some issues: - closure variables were not tracked - scoped expression variables were initialized to None So, I should fix broken tests, here are some of them: nogil (should be fixed) purecdef (upstream) cfunc_directive_in_pyclass (upstream) bufaccess_noassignT444 (should be removed?) bufaccess (should be fixed) ass2longlong (should be fixed) builtinfuncs (should be fixed) extcmethcall (should be fixed) extcoerce (fixed or removed?) e_extweakref (should be fixed) -- vitja.