cmake: older emscripten releases have a broken FindOpenGL.cmake This is fixed since 3.1.10: https://github.com/emscripten-core/emscripten/commit/485a7b4d6f84d4bc3b594ff81d39b6b143c8d598#diff-034f4d123f23ec5493d0fbf28cba1c36e404a991f286c8d031a22799e4e8b0e5