ci: add continue-on-error Redox job

[xtqqczze]

Contributes to #5210.

RUSTC_BOOTSTRAP=1 cargo check -q -Zbuild-std --all-targets --features feat_os_unix_redox --target i586-unknown-redox --target x86_64-unknown-redox

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/date/resolution (passes in this run but fails in the 'main' branch)

[xtqqczze]

@willnode Any suggestions you can make here?

[codspeed]

Merging this PR will improve performance by 6.67%

⚠️ 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

• sort_unique_utf8_locale
• du_deep_tree[(100, 3)]
• cksum_default
• dd_copy_64k_blocks
• df_deep_directory
• cksum_multiple_files
• cksum_crc32b
• dd_copy_partial
• cksum_sysv
• factor_large_u64_prime
• …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]

⚡ 1 improved benchmark
✅ 400 untouched benchmarks
⏩ 70 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	factor_three_39_bit_primes	567 ms	531.5 ms	+6.67%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing xtqqczze:ci-redox (d1aacc2) with main (7654e67)}

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]

@willnode This branch compiles locally, but the redox CI job is failing:

sccache: error: failed to execute compile
sccache: caused by: Compiler not supported: "/home/runner/.redoxer/x86_64-unknown-redox/toolchain/bin/rustc: error while loading shared libraries: libLLVM.so.21.1: cannot open shared object file: No such file or directory\n"

Should we avoid using redoxer?