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

[Heejin Ahn via cfe-commits]

aheejin wrote:

With these parameters gone, now we have this warning: (`-Wc23-extensions` is enabled by default unless you use `-std=c23`)
```console
.../libunwind/src/Unwind-wasm.c:105:62: error: omitting the parameter name in a function
  definition is a C23 extension [-Werror,-Wc23-extensions]
    105 | _LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *, uintptr_t) {}
        |
```

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