message: Use Vulkan bool type for material specialization
  Refs
diff: @@ -574,7 +574,7 @@ void VulkanExample::preparePipelines()
  for (auto &material : glTFScene.materials) {
  struct MaterialSpecializationData {
  - bool alphaMask;
  + VkBool32 alphaMask;
  float alphaMaskCutoff;
  } materialSpecializationData;
  