[libunwind] Silence -Wunused-parameter warnings in Unwind-wasm.c (PR #125412)

[Louis Dionne via cfe-commits]

https://github.com/ldionne commented:

IMO this is reasonable but it's simpler to drop the parameter names in this case, no need for `[[maybe_unused]]`.

https://github.com/llvm/llvm-project/pull/125412