gh-148200: fix warning on missing safe memzero() on CYGWIN

[carlo-bramini]

This patch fixes issue #148200.

• Issue: CYGWIN: warning on missing safe memzero() is printed #148200

[bedevere-app]

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[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[carlo-bramini]

I have not added a news entry because this seems to me an extremely trivial change, however let me know if this could be required. Thank you very much.

[picnixz]

For this, I think we should rather change upstream. I think we changed those values upstream instead (I don't want to diverge from HACL* sources in general).

cc @protz