Blender Git Loki

Cycles: Remove Vector input on Sky texture when using the included sun

When using the sun, we need to sun sampling logic to avoid excessive
sampling map resolution, but that logic assumes that the Vector input
comes from the view direction.
That is the case in the vast majority of cases anyways, so the easiest
solution is to just remove the input for that case.

Differential Revision: https://developer.blender.org/D8091