UnityExtensions Why do these DLLs end up in Android build? HoloLens?

When I build a new empty project (+use micro mscorlib) in Unity 5.6.5p4 for Android and analyze the used assets in %LOCALAPPDATA%\Unity\Editor\Editor.log I can see the following DLLs end up in the build:

UnityExtensions/Unity/Networking/UnityEngine.Networking.dll
UnityExtensions/Unity/UnityHoloLens/RuntimeEditor/UnityEngine.HoloLens.dll
UnityExtensions/Unity/UnityHoloLens/Runtime/UnityEngine.HoloLens.dll
UnityExtensions/Unity/TestRunner/UnityEngine.TestRunner.dll
UnityExtensions/Unity/Advertisements/UnityEngine.Advertisements.dll
UnityExtensions/Unity/UnityAnalytics/UnityEngine.Analytics.dll
UnityExtensions/Unity/UnityPurchasing/UnityEngine.Purchasing.dll

As I said, it's a new and empty project. No scripts that use any network capabilities. Never used the TestRunner. Analytics were set to off at project creation. No ads, No purchasing activated. And what about HoloLens, in Android?

Why do these DLLs end up in the build and how can I avoid it?

 

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