MacOS X manage universal

[Lecrapouille]

elif env['platform'] == 'osx':
    # Use Clang on macOS by default
    env['CXX'] = 'clang++'

    if env["macos_arch"] == "universal":
        env.Append(LINKFLAGS=["-arch", "x86_64", "-arch", "arm64"])
        env.Append(CCFLAGS=["-arch", "x86_64", "-arch", "arm64"])
    else:
        env.Append(LINKFLAGS=["-arch", env["macos_arch"]])
        env.Append(CCFLAGS=["-arch", env["macos_arch"]])