[llvm] [WebAssembly] Implement addrspacecast to funcref (PR #166820)

[Derek Schuff via llvm-commits]

dschuff wrote:

Looks like this test is failing in the LLVM configuration with the expensive checks enabled. I'm going to go ahead and revert it for now. If you build with that configuration (see the EXPENSIVE_CHECKS flag in https://llvm.org/docs/CMake.html) it should be pretty easy to reproduce. Then we can reland it.

https://github.com/llvm/llvm-project/pull/166820