ucontext_t, mcontext_t is missing for powerpc64le-unknown-linux-gnu

[mgiessing]

It seems ucontext_t is missing for powerpc64le-unknown-linux-gnu:

[...]
error[E0432]: unresolved import `libc::ucontext_t`
 --> unwind-sys/src/powerpc64.rs:1:5
  |
1 | use libc::ucontext_t;
  |     ^^^^^^^^^^^^^^^^ no `ucontext_t` in the root
[...]

When I check for different archs (e.g. aarch64, loongarch, riscv64) most seem to have it in their align.rs (unix/linux_like/linux/gnu/b64/<ARCH>/align.rs) file, but for Power it's missing.

System

$ rustc -vV
rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: powerpc64le-unknown-linux-gnu
release: 1.81.0
LLVM version: 18.1.7