[clang] [WebAssembly] Enable multivalue and reference-types in generic CPU config (PR #80923)

[Derek Schuff via cfe-commits]

dschuff wrote:

I think "generic" is the default CPU so object files will have it enabled by default. You can still specify "mvp" as the CPU as before to avoid it.

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