cksum: Fix -a blake3/shake*

[oech3]

I really want remove them completely since it has a maintainance cost, but broken cksum is one of a blocker for hashsum deletion. So I fix it.

Closes #10002

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/shuf/shuf-reservoir (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/sort/sort-stale-thread-mem (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[codspeed-hq]

Merging this PR will degrade performance by 99.77%

❌ 1 regressed benchmark
✅ 141 untouched benchmarks
⏩ 180 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	cksum_blake3	216.1 µs	93,266 µs	-99.77%

---

_{Comparing oech3:ckb3 (acbef91) with main (42b2ad8)}

Footnotes

1. 180 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]

Note that we are benchmarking a bunch of errors currently. So regression is not happening.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/ls/abmon-align. tests/ls/abmon-align is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/tty/tty-eof (fails in this run but passes in the 'main' branch)

[oech3]

ok?