[3.8] bpo-39033: Fix NameError in zipimport during hash validation (GH-17588)

[tirkarthi]

Fix NameError in zipimport during hash validation and add a regression test.

(cherry picked from commit 79f02fe)

https://bugs.python.org/issue39033

Automerge-Triggered-By: @encukou

[tirkarthi]

Attaching steps I followed to create the backport. Verified that reverting to older importlib file causes NameError in test as expected.

$ git checkout -b backport-79f02fe-3.8 upstream/3.8
$ git cherry-pick -x 79f02fee1a542c440fd906fd54154c73fc0f8235
$ git checkout HEAD Python/importlib_zipimport.h # Revert to HEAD and regenerate file to avoid conflicts.
$ make regen-importlib
$ git add -u .
$ git cherry-pick --continue

[serhiy-storchaka]

You are already in the list.

[tirkarthi]

It was a result of the cherry pick. I will remove it here for conflicts with other PR sorting results. Thanks.