Fix missing SO_* values

[snogge]

Some identifiers for #4148 was missing, and this was not detected because verify-build does not rebuild when
RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64=1 is set.

Fix the verify-build task by using a separate target-dir and add the missing identifiers

This is probably not the best way of structuring the CI steps, it could also be set up using a matrix in the verify-build task of ci.yml.

Sources

https://github.com/torvalds/linux/blob/master/arch/mips/include/uapi/asm/socket.h#L125
https://github.com/torvalds/linux/blob/master/arch/powerpc/include/uapi/asm/socket.h
https://github.com/torvalds/linux/blob/master/tools/include/uapi/asm-generic/socket.h

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

[rustbot]

r? @tgross35

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[tgross35]

Instead of the changes to this file, could you add println!("cargo:rerun-if-env-changed=RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64") to build.rs?

[snogge]

I've pushed an attempt. It seems to trigger rebuilds, but I'm not sure it's in the right place.

[tgross35]

Do you just mean the right place within build.rs? If so, I would put it immediately before/after the env is read at let linux_time_bits64 = env::var("RUST_LIBC_UNSTABLE_LINUX_TIME_BITS64").is_ok(); so it's easy to see they go together.

LGTM otherwise, note that CI will fail until a rust-lang/rust fix gets into nightly.

[snogge]

That was my question. I moved things around a bit to collect the linux_time_bits64 stuff in one place as much as possible.

[tgross35]

Thanks for following up, this looks good to merge as soon as CI gets fixed.