split: Reduce malloc

[oech3]

Found at #10954

[codspeed-hq]

Merging this PR will improve performance by 19.82%

⚡ 1 improved benchmark
✅ 287 untouched benchmarks
⏩ 38 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Memory	split_number_chunks	1,127.9 KB	941.3 KB	+19.82%

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_{Comparing oech3:split-malloc (2157181) with main (2993148)}

Footnotes

1. 38 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. ↩

[oech3]

Why RAM instead of speed?

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/tail/retry. tests/tail/retry is passing on 'main'. Maybe you have to rebase?
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/misc/io-errors is no longer failing!