install: give files the policy's default context under -Z

[abendrothj]

Closes #15091

Based on #15333.

With -Z, install labelled a new file from its parent directory's context, and turned any type containing tmp into user_home_t, instead of asking the policy as GNU does. It now sets the policy's default after the copy, as -d -Z does for an existing directory, and keeps the kernel's label where the policy has none. The parent-derived helper is removed.

Checked on Fedora (enforcing) against GNU 9.12: install -Z f /tmp/f is now user_tmp_t (was user_home_t), and a file in an etc_t directory under $HOME gets user_home_t (was etc_t). Added two tests that fail without the change.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/usage_vs_getopt (fails in this run but passes in the 'main' branch)

[codspeed]

Merging this PR will regress 1 benchmark

⚠️ 119 benchmarks spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

• sort_unique_utf8_locale
• cksum_default
• dd_copy_partial
• du_wide_tree[(5000, 500)]
• du_deep_tree[(100, 3)]
• df_deep_directory
• du_all_wide_tree[(5000, 500)]
• cksum_multiple_files
• cksum_crc32b
• b64_encode_synthetic
• …and 109 more

ℹ️ 1 benchmark has no flame graph

The flamegraph could not be generated because too much time was spent in runtime internals, making the visualization not useful for performance analysis.

• sort_dictionary_order[500000]

⚡ 2 improved benchmarks
❌ 1 regressed benchmark
✅ 398 untouched benchmarks
⏩ 70 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	factor_five_38_bit_primes	1.6 s	1.9 s	-12.47%
⚡	Simulation	factor_three_39_bit_primes	567 ms	449.3 ms	+26.18%
⚡	Simulation	factor_thirteen_39_bit_primes	9.5 s	9.1 s	+4.42%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing abendrothj:install-context-files (4a1a28b) with main (c76f272)}

Footnotes

1. 70 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. ↩