To reproduce:
1. Make sure you have installed Vuforia's Support (Player Settings -> XR settings -> Vuforia Augmented Reality)
2. Create an empty project
3. Switch platform to iOS
4. In player settings enable Vuforia's support
5. In hierarchy window right click then select Vuforia -> AR Camera
6. It will ask to import Vuforia's package so import it
7. Go to player settings -> Other Settings and check Camera Usage Description field

Expected: Value of this field should be set to a default one.
Actual: Value remains null and project doesn't build.

Reproduced with: 2017.2.0f3, 2017.3.0b4
Earlier versions don't include built-in Vuforia support.

Fixed in: 2018.1.0a5