[clang] [WebAssembly] Add more features to generic CPU config (PR #80923)

[Sam Clegg via cfe-commits]

sbc100 wrote:

> Tried running Emscripten tests, and some of them fail with reference-types or bulk-memory. I haven't investigated the causes yet, but it could be better to start with the other two (nontrapping-fptoint and multivalue).

No need to block these on emscripten failures.. I'm sure we can find and fix those.   We should make this decision based on current browser stats and release dates I think,

https://github.com/llvm/llvm-project/pull/80923