Skip generating emscripten stack functions if they already exist (#2853)
Skip generating emscripten stack functions if they already exist (#2853)

This should allow https://github.com/emscripten-core/emscripten/pull/11166
to land, afterwhich we can completely remove these functions.
WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen