linux_like(android,linux): remove af_alg_iv unsound implementations in extra_traits feature

[dybucc]

Description

Closes #1501. See that issue for details on the
unsoundness report. That was fixed a while ago on main but the patch
would have broken stable, so a deprecation warning was applied instead.
Follows a brief discussion at
#1501 (comment).

Note the automatically-derived implementations for Debug and Clone
for this type seem odd now. The last member is a FAM upstream, so I
think Debug can just live with that, but Clone wouldn't feel right
to provide without some word of warning to users about the "extended"
length beyond the trailing struct member not being copied over to
the new instance of the type. I guess downstream users can then use a
newtype to implement Clone as they see fit; The fields on af_alg_iv
are public, after all.

Checklist

• Relevant tests in libc-test/semver have been updated
• Commit messages permalink to headers for added or changed API
• Placeholder or unstable values like *LAST or *MAX have the
  standard doc comment
• Tested locally (cargo test -p libc-test --target mytarget);
  especially relevant for platforms that may not be checked in CI

@rustbot label +stable-nominated

[rustbot]

Some changes occurred in an Android module

cc @maurer

[rustbot]

⚠️ Warning ⚠️

• Pull requests are usually filed against the main branch for this repo, but this one is against libc-0.2. Please double check that you specified the right target!

[tgross35]

LGTM, thanks! Will merge as part of the next release's backports

View changes since this review

[tgross35]

No need to update this but for future reference, if you mention a commit sha in a commit message it's good to include a abcd12345678 ("Title of the commit") to hint what it's about, and to help the message survive any unlikely but possible force pushes. (Mentioned at https://docs.kernel.org/process/submitting-patches.html#describe-your-changes, I usually do the 12 characters.)

[rustbot]

This PR was rebased onto a different libc-0.2 commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.