Linux build for OVR oculus: namespace does not exist

Target Platforms XR
1

Iam building my project from commandline:

"C:\Program Files\Unity\Editor\Unity.exe" -batchmode -quit -buildLinux64Player ../bin/Linux64_program -logFile winBuild.log

EDIT:
The same happens if i build in the Editor.

And get those errors:

Assets/External/OVR/Scripts/OVRCameraRig.cs(137,38): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCameraRig.cs(138,87): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCameraRig.cs(139,82): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCameraRig.cs(144,38): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCameraRig.cs(145,81): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCameraRig.cs(146,82): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCommon.cs(38,38): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRCommon.cs(39,41): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRDebugHeadController.cs(93,12): error CS0234: The type or namespace name `VRDevice' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/OVRDisplay.cs(101,12): error CS0234: The type or namespace name `InputTracking' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/Util/OVRDebugInfo.cs(379,20): error CS0234: The type or namespace name `VRSettings' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/Util/OVRSceneSampleController.cs(151,39): error CS0234: The type or namespace name `VRSettings' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
Assets/External/OVR/Scripts/Util/OVRSceneSampleController.cs(151,7): error CS0234: The type or namespace name `VRSettings' does not exist in the namespace `UnityEngine.VR'. Are you missing an assembly reference?
2

Just see that this happens in the Unity Editor too…

3

This is happening to me as well in Unity 5.5.2 when attempting to build for Linux x64 with the VRSettings namespace.