tail calls

[unicomp21]

@tlively, the tail call support in binaryen, does that mean I can do co_wait stuff now? I also noticed in the blazor.net stuff they also managed to implement the "tail" instruction somehow for webassembly?

[tlively]

See previous discussion at emscripten-core/emscripten#10991. LLVM and Binaryen support tail calls, but I don't believe they have been shipped in any Web engine yet, so you can't actually use them in practice. It's possible co_wait will just work but be inefficient or sometimes exhaust the stack, but I haven't tried.