cp/mv: suppress xattr ENOTSUP errors for optional preservation

[ChrisDryden]

If a filesystem is unable to modify xattr in files with specific flags in mv and cp it is supposed to silently fail and not throw an error. There is a GNU test that tests this behaviour that has been failing and this change should address all of the expectations of the tests.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Congrats! The gnu test tests/dd/nocache_eof is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/shuf/shuf-reservoir. tests/shuf/shuf-reservoir is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/sort/sort-stale-thread-mem. tests/sort/sort-stale-thread-mem is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/shuf/shuf-reservoir. tests/shuf/shuf-reservoir is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/sort/sort-stale-thread-mem. tests/sort/sort-stale-thread-mem is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/cp/cp-mv-enotsup-xattr is no longer failing!

[codspeed-hq]

Merging this PR will degrade performance by 7.99%

❌ 1 regressed benchmark
✅ 281 untouched benchmarks
⏩ 38 skipped benchmarks¹

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

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	cp_large_file[16]	110.7 KB	120.3 KB	-7.99%

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_{Comparing ChrisDryden:cp-mv-xattr-enotsup-tests (13aab97) with main (7654075)²}

Footnotes

1. 38 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. ↩

2. No successful run was found on main (309e3be) during the generation of this report, so 7654075 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩