Add buffered printing and lock output stream to tsort

[mrkalling]

This pull request adds buffered output and locks stdout during printing to improve performance. As a side effect, tsort no longer panics when printing to stdout fails.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/pipe-f (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/tail-n0f (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/date/date-locale-hour (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/expand/bounded-memory is now passing!

[codspeed-hq]

Merging this PR will improve performance by 10.15%

⚡ 6 improved benchmarks
✅ 303 untouched benchmarks
⏩ 60 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	tsort_tree_dag[(10, 3)]	29.1 ms	25.3 ms	+15.23%
⚡	Simulation	tsort_wide_dag[100000]	116 ms	102.4 ms	+13.28%
⚡	Simulation	tsort_linear_chain[1000000]	1.4 s	1.3 s	+10.38%
⚡	Simulation	tsort_complex_dag[50000]	73.3 ms	66.8 ms	+9.69%
⚡	Memory	cp_recursive_deep_tree[(120, 4)]	615.6 KB	562.5 KB	+9.44%
⚡	Simulation	single_date_now	85.6 µs	82.9 µs	+3.24%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing mrkalling:martink (b3dfbf3) with main (82ff021)}

Footnotes

1. 60 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. ↩