od: stream the output line instead of buffering it

[sylvestre]

A line is padded up to the full -w width before the ascii dump, and the formatted fields themselves take about 4 bytes per input byte, so od -w3037000500 -tcz built a 12 GB String. Write the offset, the fields and the padding straight to the writer, tracking the line width as it goes instead of measuring a buffered string.

Should fix tests/od/big-w.sh

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[codspeed]

Merging this PR will improve performance by 15.18%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 3 improved benchmarks
✅ 3 untouched benchmarks
⏩ 418 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	od_default	601.3 ms	511.8 ms	+17.49%
⚡	Simulation	od_chars	948.2 ms	831.2 ms	+14.07%
⚡	Simulation	od_hex_bytes	991.8 ms	870.1 ms	+14%

Tip

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

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_{Comparing sylvestre:od-big (8c7ec47) with main (58490b3)²}

Footnotes

1. 418 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. ↩

2. No successful run was found on main (848ad09) during the generation of this report, so 58490b3 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/resolution (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)