tsort: replace nix by rustix

[oech3]

split #11548

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/rm/isatty (fails in this run but passes in the 'main' branch)
Note: The gnu test tests/seq/seq-epipe is now being skipped but was previously passing.
Congrats! The gnu test tests/cut/bounded-memory is now passing!
Congrats! The gnu test tests/tail/pipe-f is now passing!