std lib build broken for uclibc

[asomers]

Commit 33fd73f appears to have broken the build for uclibc. This command fails:

cargo +nightly check -Zbuild-std --target armv7-unknown-linux-uclibceabihf
...
error[E0599]: no method named `si_addr` found for struct `siginfo_t` in the current scope
  --> /usr/local/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/unix/stack_overflow.rs:84:28
   |
84 |         let addr = (*info).si_addr() as usize;
   |                            ^^^^^^^ method not found in `siginfo_t`

The problem is that libc does not define that field for uclibc. Whether that's an oversight in libc, or whether uclibc itself doesn't define that field, I don't know.

[asomers]

@skrap can you figure out whether the problem is in libc or uclibc itself?

[name1e5s]

@skrap can you figure out whether the problem is in libc or uclibc itself?

It seems that libc doesn't implement fn si_addr in siginfo_t for uclibc, maybe we should partially revert #95688

[skrap]

@skrap can you figure out whether the problem is in libc or uclibc itself?

It seems that libc doesn't implement fn si_addr in siginfo_t for uclibc, maybe we should partially revert #95688

I'll have a look! Thanks for the CC!

[skrap]

Looks like @pfmooney has a good-looking PR out to add those accessors into libc!

[pfmooney]

After the next release of libc, whenever that may be, the change from the now-integrated rust-lang/libc#2750 should help address this. A stopgap fix might be justified in the mean time.