[clang] [llvm] [WebAssembly] Implement an alternative translation for -wasm-enable-sjlj (PR #84137)

[Heejin Ahn via cfe-commits]

aheejin wrote:

Had a chance to chat with @sbc100 offline and we agreed we can probably do this:

> 1. Add library functions in emscripten
> 2. Replace the current logic in LLVM with new code. (Without `if`~`else`). Tests can be updated with this.
> 3. Remove old library functions in emscripten.

The downside of this approach is when you add library functions in emscripten we can't add tests with them. But given that we will follow up with the LLVM side PRs I think it should be fine. Also this removes the need to duplicate tests in LLVM (or omit tests in LLVM when this lands).

https://github.com/llvm/llvm-project/pull/84137