gh-103167: Fix -Wstrict-prototypes warnings by using (void) for functions with no args

[sobolevn]

Are there any others that I've missed?

• Issue: -Wstrict-prototypes warnings on macOS #103167

[encukou]

LGTM. I've grepped all of these to check they're only called with no arguments.
But since this touches platform-specific code, let's ask the buildbots before merging.

Are there any others that I've missed?

If there are they can always go in a different PR.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @encukou for commit eae4660 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

[sobolevn]

@encukou done! 👍