[llvm] [WebAssembly] Disable multivalue emission temporarily (PR #82714)

[Derek Schuff via llvm-commits]

dschuff wrote:

For this use case we could make the experimental MV ABI flag also enable `wasm-emit-multivalue`? Otherwise the ABI flag wouldn't be able to do anything anyway. We could maybe also, instead of making multivalue-emission default-off in LLVM, make it default-on in LLVM but make clang disable it by default? That would eliminate disruption to non-clang LLVM users (although such users would then still be disrupted by needing to enable MV if they needed to use EH... but maybe any EH users are going to be disrupted one way or another anyway...).

https://github.com/llvm/llvm-project/pull/82714