[clang] [clang][WebAssembly] Support the `-m(no-)red-zone` flag. (PR #119997)

[Dan Gohman via cfe-commits]

sunfishcode wrote:

Is there a use case that needs to disable the red zone globally on Wasm? My understanding is that -mno-red-zone exists for compatibility reasons that don't apply to Wasm. I'm hesitant to add flags adding implicit ABI variants in the absence of use cases. At least with the function attribute it's explicit in the code.

https://github.com/llvm/llvm-project/pull/119997