[llvm] [WebAssembly] Enable multivalue return when multivalue ABI is used (PR #88492)

[Derek Schuff via llvm-commits]

https://github.com/dschuff approved this pull request.

Changes LGTM.
I think the title or commit description should probably mention that this just applies to libcalls (since MV return is already controlled by the ABI option for other calls).

https://github.com/llvm/llvm-project/pull/88492