linux: gnu/musl: MAP_32BIT is only defined on x86

[Gelbpunkt]

Description

The Linux kernel only defines MAP_32BIT in the asm/mman.h header on x86. Remove the erraneous definitions for any other architectures on Linux targets.

This makes libc-test somewhat compile on powerpc64le musl (except semver, I'll follow up on that as well).

Sources

See https://github.com/torvalds/linux/blob/master/arch/x86/include/uapi/asm/mman.h#L5

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI

^ didn't test the other two targets, but this is definitely correct. semver tests only tested for this on x86 already

[tgross35]

For mk68 and wasm-wali I'm okay to drop this immediately. I think we should give a warning to powerpc users though, could you mark this deprecated instead on that platform?

If it's causing test failures, just add it as a skip in libc-test/build.rs

[Gelbpunkt]

I think we should give a warning to powerpc users though, could you mark this deprecated instead on that platform?

Even for the main branch? I get that'd be good for 0.2, just wondering why that'd be the case for the development branch

[tgross35]

Yes please; that just makes things easier for the time being since the branches remain more in sync (read: fewer conflicts for me to resolve doing cherry picks), it will be easy to delete all deprecated items once we get closer to 1.0.

[Gelbpunkt]

Should be done now, please double-check the deprecation message

[tgross35]

Thanks!