Right - this fails in vkd3d as there's no d3d12sdklayers.{idl,h} there.
There is, but it's called vkd3d_d3d12sdklayers.idl. I'm not quite sure why this #include wasn't added back when it was introduced by commit 332b250e82a16bd1f5d6eec7659a834604452ec2. I suspect it was just an oversight, but it's also possible that the SDK headers simply changed in this regard.