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

[Sam Clegg via cfe-commits]

sbc100 wrote:

In several other places in libunwind it looks like more basic methods of supporssing this warning are used: https://github.com/llvm/llvm-project/blob/3bf53844cfedf09f22d2786e57ef81d5d41fe249/libunwind/src/AddressSpace.hpp#L465-L466

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