Stdarch support for wasm32-wali-linux-musl Tier-3 Linux target

[arjunr2]

To support the new Tier-3 target wasm32-wali-linux-musl within the rust compiler : rust-lang/rust#135651

Minimally, this just disables dynamic-linking related Linux features which is not supported yet in Wasm.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Amanieu (or someone else) some time within the next two weeks.

[sayantn]

Please rebase

[bjorn3]

Is there a reason wali doesn't provide getauxvval?

[arjunr2]

Is there a reason wali doesn't provide getauxvval?

Wasm doesn't have a dynamic linking specification yet. These features can be added back in the future once supported

[bjorn3]

Directly linking to getauxval rather than using dlsym should work if libc for wali is guaranteed to support it, right? The only reason std_detect is using dlsym is because older libc versions for some targets don't support getauxval.

[arjunr2]

That's true, we could probably just disable std_detect_dlsym_getauxval when building stdarch for rustc. That should work right?

WALI libc does expose getauxval but support for it is not fully specified/handled yet (particularly architecture-specific types/values) As such, preventing it from being called for the time being is preferable.