opencomposite: fix build

  cmakeFlags = [

    (lib.cmakeBool "USE_SYSTEM_OPENXR" true)

    (lib.cmakeBool "USE_SYSTEM_GLM" true)

    (lib.cmakeFeature "CMAKE_CXX_FLAGS" "-DGLM_ENABLE_EXPERIMENTAL")

    # debug logging macros cause format-security warnings

    (lib.cmakeFeature "CMAKE_CXX_FLAGS" "-Wno-error=format-security")

  ];

  # NOTE: `cmakeFlags` will get later tokenized by bash and there is no way

  # of inserting a flag value with a space in it (inserting `"` or `'` won't help).

  # https://discourse.nixos.org/t/cmakeflags-and-spaces-in-option-values/20170/2

  preConfigure = ''

    cmakeFlagsArray+=(

      "-DCMAKE_CXX_FLAGS=-DGLM_ENABLE_EXPERIMENTAL -Wno-error=format-security"

    )

  '';

  installPhase = ''

    runHook preInstall

    mkdir -p $out/lib/opencomposite