cksum: disable a broken benchmark

[oech3]

No description provided.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/seq/seq-epipe is now passing!

[codspeed-hq]

Merging this PR will degrade performance by 3.46%

❌ 1 regressed benchmark
✅ 301 untouched benchmarks
⏩ 44 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	true_no_args	813.3 ns	842.5 ns	-3.46%

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_{Comparing oech3:patch-1 (a72ffbc) with main (1f7c81f)}

Footnotes

1. 44 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:

GNU test failed: tests/seq/seq-epipe. tests/seq/seq-epipe is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cut/bounded-memory is now passing!