numfmt: reduce malloc

[oech3]

numfmt_to_si_precision[10000] +2%
numfmt_to_si[10000] +1%
numfmt_from_si[10000] +1%
numfmt_round_modes[("up", 10000)] +1%
numfmt_round_modes[("towards-zero", 10000)] +1%
numfmt_round_modes[("down", 10000)] +1%
numfmt_large_numbers_si[10000] +1%
numfmt_padding[(10000, 50)] 0% 51.3 ms -> 51.1 ms
numfmt_to_iec[10000] 0% 35.4 ms -> 35.3 ms

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/cut/bounded-memory is no longer failing!
Note: The gnu test tests/unexpand/bounded-memory is now being skipped but was previously passing.

[codspeed-hq]

Merging this PR will not alter performance

✅ 288 untouched benchmarks
⏩ 40 skipped benchmarks¹

---

_{Comparing oech3:numfmt-malloc (ef0fca7) with main (6633ab8)}

Footnotes

1. 40 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:

Congrats! The gnu test tests/date/date-locale-hour is no longer failing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/date/date-locale-hour. tests/date/date-locale-hour is passing on 'main'. Maybe you have to rebase?

[xtqqczze]

I noticed we can remove the buffer completely, opened #11051

[oech3]

OK to close this. Right?

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/tail/retry is no longer failing!