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

[Louis Dionne via cfe-commits]

================
@@ -116,7 +117,7 @@ _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
 
 /// Not used in Wasm.
 _LIBUNWIND_EXPORT uintptr_t
-_Unwind_GetRegionStart(struct _Unwind_Context *context) {
+_Unwind_GetRegionStart([[maybe_unused]] struct _Unwind_Context *context) {
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ldionne wrote:

```suggestion
_Unwind_GetRegionStart(struct _Unwind_Context *) {
```

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