message: Optionally use LBVH w/ AO example
diff: @@ -71,7 +71,8 @@ struct renderer : viewer_type
  add_cmdline_option( cl::makeOption<bvh_build_strategy&>({
  { "default", Binned, "Binned SAH" },
  - { "split", Split, "Binned SAH with spatial splits" }
  + { "split", Split, "Binned SAH with spatial splits" },
  + { "lbvh", LBVH, "LBVH (CPU)" }
  },
  "bvh",
  cl::Desc("BVH build strategy"),
  @@ -99,7 +100,8 @@ struct renderer : viewer_type
  enum bvh_build_strategy
  {
  Binned = 0, // Binned SAH builder, no spatial splits
  - Split // Split BVH, also binned and with SAH
  + Split, // Split BVH, also binned and with SAH
  + LBVH, // LBVH builder on the CPU
  };
  pinhole_camera cam;
  