replace memchr with bytecount

[xtqqczze]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 309 untouched benchmarks
⏩ 46 skipped benchmarks¹

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_{Comparing xtqqczze:bytecount (c4fed3f) with main (3194190)}

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. ↩

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/misc/io-errors is no longer failing!
Note: The gnu test tests/cut/cut-huge-range is now being skipped but was previously passing.
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[oech3]

I'm considering to replace cat bench with head bench for this.
cat bench cannot be used for non-linux since it uses splice().
head -n cannot splice.

[xtqqczze]

Merging this PR will not alter performance

That's surprising since replacing bytecount with memchr was a regression: #11871.