Issue #20160: Merged fix from 3.3.

diff --cc Lib/ctypes/test/test_callbacks.py
index 3824f7c9fd9e407cf1f132f5851dcedcc9133ba6,4ca50b8defb814d2b773b6faf4b30a59bed58940..8eac58f0262cafdca1835dbeeb52290a0e50c490
--- 1/Lib/ctypes/test/test_callbacks.py
--- 2/Lib/ctypes/test/test_callbacks.py
+++ b/Lib/ctypes/test/test_callbacks.py
@@@ -1,6 -1,6 +1,7 @@@
+ import functools
  import unittest
  from ctypes import *
 +from ctypes.test import need_symbol
  import _ctypes_test
  
  class Callbacks(unittest.TestCase):

diff --cc Modules/_ctypes/_ctypes_test.c
Simple merge

diff --cc Modules/_ctypes/libffi_msvc/ffi.c
Simple merge