Check for Vulkan Memory Model support and make it a variant.

drivers/d3d12/rendering_device_driver_d3d12.cpp

@@ -5588,6 +5588,8 @@ bool RenderingDeviceDriverD3D12::has_feature(Features p_feature) {
 			return true;
 		case SUPPORTS_IMAGE_ATOMIC_32_BIT:
 			return true;
+		case SUPPORTS_VULKAN_MEMORY_MODEL:
+			return false;
 		default:
 			return false;
 	}