tac: use temp file for stdin to respect TMPDIR and handle disk-full errors

[ChrisDryden]

The tac-continue test used to rely on having an accessible TMP_DIR, the test was changed and now it was updated to be more flexible. Ultimately the functionality of tac in our implementation compared to the GNU implementation was just different from the context that the stdin is buffered to a TMP_DIR in the GNU implementation and not in the uutils implementation. This can cause issues with large STDIN because it will always max out the memory and timeout instead of erroring and it takes up significantly more memory.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/tac/tac. tests/tac/tac is passing on 'main'. Maybe you have to rebase?

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/tac/tac-continue is now passing!

[codspeed-hq]

CodSpeed Performance Report

Merging this PR will improve performance by 3.86%

_{Comparing ChrisDryden:tac-stdin-tempfile (61788e3) with main (20a5c3a)}

Summary

⚡ 1 improved benchmark
✅ 139 untouched benchmarks
⏩ 37 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	tsort_input_parsing_heavy[5000]	73.7 ms	71 ms	+3.86%

Footnotes

1. 37 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/tac/tac-continue is now passing!