Apparently 10.11 is no longer good enough to run the latest version of binaryen. Specifically since binaryen switched to using std::variant it now fails to build with this set to 10.11. This is also the version used on the emscripten-releases CI which builds the emsdk binaries: https://chromium.googlesource.com/emscripten-releases/+/refs/heads/main/src/build.py#673