[WebAssembly] Error when wasm EH is used with Emscripten EH/SjLj
- Error out when both Emscripten EH and wasm EH are used together, i.e.,
both `-enable-emscripten-cxx-exceptions` and `-exception-model=wasm`
are given together. This will not happen if you use Emscripten, but
this can happen when you call `llc` manually with wrong set of
arguments.
- Currently we don't yet support using wasm EH with Emscripten SjLj.
Unlike `-enable-emscripten-cxx-exceptions` which is turned on only
when you use `emcc -s DISABLE_EXCEPTION_CATCHING=0`,
`-enable-emscripten-sjlj` is turned on by Emscripten by default. So we
error out only when it is turned on and `setjmp` or `longjmp` is
actually used.
Reviewed By: tlively
Differential Revision: https://reviews.llvm.org/D101403