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

[YAMAMOTO Takashi via cfe-commits]

yamt wrote:

@aheejin @sbc100
i think i resolved most of your feedback in this PR and the emscripten PR.

i tried to run the relevant emscripten tests. but i have not succeeded yet even w/o these changes. (i'm an emscripten newbie.)


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