example_emscripten: skip outdated compiler option
example_emscripten: skip outdated compiler option

For more info see: https://github.com/ocornut/imgui/issues/2877

ggtucker/imgui,ocornut/imgui,ggtucker/imgui,bkaradzic/imgui,aimotive/imgui-glfw,nProtect/imgui,bkaradzic/imgui,nProtect/imgui,Flix01/imgui,Flix01/imgui,aimotive/imgui-glfw,ggtucker/imgui,ocornut/imgui,bkaradzic/imgui,dougbinks/imgui,ocornut/imgui,nProtect/imgui,dougbinks/imgui,Flix01/imgui