uucore: detect CPU features on Android

[limadog9]

Use Rust's supported feature detection on Android instead of disabling every feature. Enable the checksum debug tests there and add an x86_64 SSE2 regression that runs in the existing Android CI.

Closes #15233

[codspeed]

Merging this PR will regress 1 benchmark

⚠️ 120 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

• cksum_default
• du_wide_tree[(5000, 500)]
• dd_copy_partial
• factor_multiple_u64s[2]
• cksum_multiple_files
• cksum_crc32b
• dd_copy_64k_blocks
• cksum_sysv
• du_all_wide_tree[(5000, 500)]
• dd_copy_1m_blocks
• …and 110 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_thirteen_39_bit_primes	8.7 s	9.3 s	-7.13%
⚡	Simulation	factor_three_39_bit_primes	800.7 ms	525.2 ms	+52.45%
⚡	Simulation	factor_five_38_bit_primes	1.8 s	1.7 s	+5.09%

Tip

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

---

_{Comparing limadog9:fix/hardware-android-detection (34575d5) with main (2fb77e8)}

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. ↩

[xtqqczze]

factor benchmark variance tracked by #14921.