add shim for avx512 ternarylogic functions

[folkertdev]

Adds the first dedicated avx512 shim, so that requires some setup.

The ternary logic functions are used in avx512 crc32 implementations, I'm specifically implementing one in zlib-rs right now.

[rustbot]

Thank you for contributing to Miri! A reviewer will take a look at your PR, typically within a week or two.
Please remember to not force-push to the PR branch except when you need to rebase due to a conflict or when the reviewer asks you for it.

[RalfJung]

Thanks! I meant to add more tests, not replace the existing ones. But this is fine too as long as all 3 are covered. The masking seems to be implemented in stdtach so we don't really need to test that here. Did you confirm these on real HW?

[RalfJung]

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[RalfJung]

This looks great, thanks! Please squash the commits using ./miri squash. Then write @rustbot ready after you force-pushed the squashed PR.

@rustbot author

[folkertdev]

Is CI flaky here?

E: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/noble-security/main/binary-armhf/Packages.xz  File has unexpected size (442940 != 443108). Mirror sync in progress? [IP: 91.189.91.102 80]
   Hashes of expected file:
    - Filesize:443108 [weak]
    - SHA256:94e16562de548af81cd7fe9f2c811beac145a8578215679cf9e859980d78c1db
    - SHA1:0754fc5a9770987305b40d119f88cfaf4530246b [weak]
    - MD5Sum:b0e683c5e432662b34d2c45edc9822ca [weak]
   Release file created at: Tue, 11 Nov 2025 15:57:34 +0000
E: Some index files failed to download. They have been ignored, or old ones used instead.
Error: Process completed with exit code 100.

[RalfJung]

Yeah the Ubuntu ports mirrors are pretty bad, we already disabled most ports CI -- armv7 has been better so far but also sometimes fails. :/