[3.9] bpo-25655: Improve Win DLL loading failures doc (GH-22372) by miss-islington · Pull Request #22894 · python/cpython

@pombredanne @miss-islington

Add documentation to help diagnose CDLL dependent DLL loading errors
on windows for OSError with message:
"[WinError 126] The specified module could not be found"
This error is otherwise difficult to diagnose.
(cherry picked from commit b6f2fc9)

Co-authored-by: Philippe Ombredanne <pombredanne@gmail.com>