[clang] [libunwind] [libunwind][WebAssembly] Make libunwind compilable (PR #92192)

[Anton Korobeynikov via cfe-commits]

https://github.com/asl approved this pull request.

Ok from the generic point of view. I cannot judge if wasm-related part is ok though :)

https://github.com/llvm/llvm-project/pull/92192