uniq: simplify loop by while

[oech3]

No description provided.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/date/resolution (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/symlink (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/dd/no-allocate is now passing!

[codspeed-hq]

Merging this PR will degrade performance by 3.4%

⚠️ 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

❌ 1 regressed benchmark
✅ 346 untouched benchmarks
🆕 10 new benchmarks
⏩ 46 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	numfmt_large_numbers_si[10000]	94.7 ms	98.1 ms	-3.4%
🆕	Memory	ptx_input_references_short_lines[100000]	N/A	222.2 MB	N/A
🆕	Memory	ptx_long_lines[100]	N/A	29.5 MB	N/A
🆕	Memory	ptx_short_lines[100000]	N/A	240.1 MB	N/A
🆕	Memory	ptx_input_references_long_lines[1000]	N/A	29.1 MB	N/A
🆕	Memory	ptx_tex[10000]	N/A	20.6 MB	N/A
🆕	Simulation	ptx_input_references_short_lines[100000]	N/A	16.2 s	N/A
🆕	Simulation	ptx_long_lines[100]	N/A	1.7 s	N/A
🆕	Simulation	ptx_short_lines[100000]	N/A	14.1 s	N/A
🆕	Simulation	ptx_input_references_long_lines[1000]	N/A	2 s	N/A
🆕	Simulation	ptx_tex[10000]	N/A	2.9 s	N/A

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing oech3:uniq-loop (11e3236) with main (66cf72b)²}

Footnotes

1. 46 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 (e6561b5) during the generation of this report, so 66cf72b was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩