Blender Git Loki

Depsgraph: fix handling of driver variable dependencies with proxies.

During driver var evaluation, the code directly skips to the proxy
object if present, so the dependencies should reflect that, instead
of inventing extra relations to pretend as if the values were
first copied from the proxy - they actually aren't.

The invented dependencies can't work without cycles in complex but
meaningful cases, e.g. drivers on armature data that depend on pose.

This alters the changes from 72cbf966fb91 to be more correct.