tail: replace nix by rustix

[oech3]

split #11548
This might require libc-backend for LD_PRELOAD test on GnuTests i.e.
RUSTFLAGS=--cfg=rustix_use_libc.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/symlink (fails in this run but passes in the 'main' branch)
Note: The gnu test tests/csplit/csplit-heap is now being skipped but was previously passing.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/timeout/timeout-group. tests/timeout/timeout-group is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/symlink (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/csplit/csplit-heap is now passing!

[oech3]

tests/tail/symlink does not use LD_PRELOAD

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/basenc/bounded-memory is now being skipped but was previously passing.
Note: The gnu test tests/cut/cut-huge-range is now being skipped but was previously passing.
Congrats! The gnu test tests/dd/no-allocate is now passing!