cksum: get rid of print! and println! to avoid panicking on write errors

[RenjiSann]

Fix for #10947

Also needed to do some shenanigans in the uucore::bin macro to avoid having an extra flush failing.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/misc/io-errors. tests/misc/io-errors is passing on 'main'. Maybe you have to rebase?
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)
Skipping an intermittent issue tests/date/resolution (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/rm/many-dir-entries-vs-OOM is now passing!

[codspeed-hq]

Merging this PR will degrade performance by 16.98%

❌ 1 regressed benchmark
✅ 310 untouched benchmarks
⏩ 46 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	hostname_ip_lookup[100000]	90.4 µs	108.9 µs	-16.98%

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_{Comparing RenjiSann:cksum-fix-print (72c09c8) with main (45a48a1)}

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. ↩

[RenjiSann]

Note that GNU seems to inconsistenly handle whether it shows the No space left on device detail depending on the presence of the -z flag (which replace line breaks by nul bytes).

I assume this is because the way the error is displayed is different between the writes and the final flush that happens in -z mode. I don't think it's relevant to follow this behavior here.

$ uu_cksum /dev/null > /dev/full
cksum: write error: No space left on device

$ gnu_cksum /dev/null > /dev/full       
cksum: write error                               # <-- GNU most probably prints the error differently here

$ uu_cksum /dev/null > /dev/full -z
cksum: write error: No space left on device

$ gnu_cksum /dev/null > /dev/full -z       
cksum: write error: No space left on device

[xtqqczze]

$ gnu_cksum /dev/null > /dev/full
cksum: write error # <-- GNU most probably prints the error differently here

maybe you should report that to the coreutils/coreutils repo

[xtqqczze]

some shenanigans in the uucore::bin macro to avoid having an extra flush failing.

Good work with the macros, I'd been wondering whether it was possible to avoid that flush.

[RenjiSann]

$ gnu_cksum /dev/null > /dev/full
cksum: write error # <-- GNU most probably prints the error differently here

maybe you should report that to the coreutils/coreutils repo

Done ! coreutils/coreutils#258

some shenanigans in the uucore::bin macro to avoid having an extra flush failing.

Good work with the macros, I'd been wondering whether it was possible to avoid that flush.

Thanks :)
It's a bit rough but it does not make a too big change. If we need to do the same thing for other binaries, maybe I'll try to find a cleaner way to do it ^^