nl: improve the performances

[sylvestre]

hyperfine --warmup 3 "/usr/bin/nl moby64.txt"                     "./target/release/coreutils.prev nl  moby64.txt" "./target/release/coreutils nl moby64.txt"
Benchmark 1: /usr/bin/nl moby64.txt
  Time (mean ± σ):     179.8 ms ±   3.1 ms    [User: 165.6 ms, System: 14.1 ms]
  Range (min … max):   173.6 ms … 184.0 ms    16 runs

Benchmark 2: ./target/release/coreutils.prev nl  moby64.txt
  Time (mean ± σ):     380.6 ms ±   4.9 ms    [User: 278.2 ms, System: 102.2 ms]
  Range (min … max):   375.4 ms … 391.4 ms    10 runs

Benchmark 3: ./target/release/coreutils nl moby64.txt
  Time (mean ± σ):     167.3 ms ±   1.7 ms    [User: 154.5 ms, System: 12.7 ms]
  Range (min … max):   163.8 ms … 170.0 ms    17 runs

Summary
  ./target/release/coreutils nl moby64.txt ran
    1.07 ± 0.02 times faster than /usr/bin/nl moby64.txt
    2.27 ± 0.04 times faster than ./target/release/coreutils.prev nl  moby64.txt

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/overlay-headers (passes in this run but fails in the 'main' branch)

[codspeed-hq]

CodSpeed Performance Report

Merging #8811 will improve performances by 27.71%

_{Comparing sylvestre:perf-nl (8ec28bb) with main (94b6544)}

Summary

⚡ 2 improvements
✅ 75 untouched
⏩ 73 skipped¹

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	nl_large_file[10]	128.1 ms	100.6 ms	+27.34%
⚡	nl_many_lines[100000]	101.6 ms	79.5 ms	+27.71%

Footnotes

1. 73 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. ↩

[cakebaker]

Kudos for improving the performance by almost 30% :)