WASM64 compiltion failure on `core::arch::wasm32::unreachable()` in the unwind library

[newpavlov]

Compiling tests with cargo test --no-run -Z build-std=std,panic_abort results in the following compilation error:

   Compiling unwind v0.0.0 (/home/runner/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/unwind)
error[E0433]: failed to resolve: could not find `wasm32` in `arch`
  --> /home/runner/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/unwind/src/wasm.rs:62:25
   |
62 |             core::arch::wasm32::unreachable()
   |                         ^^^^^^ could not find `wasm32` in `arch`

For example, see this CI job.

Nightly version: rustc 1.79.0-nightly (0ad927c 2024-03-21)

[kadiwa4]

Fixed by #122797