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

[YAMAMOTO Takashi via cfe-commits]

yamt wrote:

> @yamt, do you want to submit a PR to emscripten adding new library functions? I can do that too, but given that this is your code, if you want to do it it'd be good. About where to add them... to make the transition smooth, https://github.com/emscripten-core/emscripten/blob/main/system/lib/compiler-rt/emscripten_setjmp.c looks like a good place to start given that our current functions are here, but we can move them later to elsewhere. WDYT? @sbc100

https://github.com/emscripten-core/emscripten/pull/21502

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