[lld] [llvm] [WebAssembly] Add target architecture to object file format (PR #225979)

[Sam Clegg via llvm-commits]

sbc100 wrote:

Here you can see where unknown subsections are ignored: https://github.com/llvm/llvm-project/blob/3a2787d5ca6ba0271f7203997f8a9b65679398a4/llvm/lib/Object/WasmObjectFile.cpp#L697-L699

https://github.com/llvm/llvm-project/pull/225979