Add ucontext_t for aarch64-unknown-linux-musl

[ifreund]

See: bytecodealliance/wasmtime#2133

[rust-highfive]

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[JohnTitor]

Use no_extra_traits due to array longer than 32

Did you test with this workaround? I guess we could auto-derive it here as well...

libc/src/unix/linux_like/linux/gnu/b64/aarch64/align.rs

Lines 25 to 27 in 035a480

	// nested arrays to get the right size/length while being able to
	// auto-derive traits like Debug
	__reserved: [[u64; 32]; 16],

[ifreund]

Did you test with this workaround? I guess we could auto-derive it here as well...

I tried it but the math doesn't work out in this case. The prime factorization of 36 + 512 is 2 * 2 * 137. Guess we could use multiple members though if that would be preferable.

[JohnTitor]

Ah, makes sense. I'd still prefer to auto-derive it as this will make the difference between arch/env and users will be confused.

[JohnTitor]

(Note that CI will fail anyway until #1865 gets merged.)

[JohnTitor]

Looks good except for spurious failures. Could you rebase and squash commits into one?

[ifreund]

@JohnTitor squashed!

[JohnTitor]

Thanks a lot!