[3.9] bpo-40998: Address compiler warnings found by ubsan (GH-20929) by miss-islington · Pull Request #23370 · python/cpython

Signed-off-by: Christian Heimes christian@python.org

Automerge-Triggered-By: GH:tiran
(cherry picked from commit 07f2ade)

Co-authored-by: Christian Heimes christian@python.org

https://bugs.python.org/issue40998

Automerge-Triggered-By: GH:tiran