Blender Git Loki

Fix T80078: Overrides: Crash with animated IK control on linked armature.

Issue was with our dear posebones again... when applying overrides we
keep the same address/pointer for the IDs themselves, (which avoids us
the need to remap their usages), but their inner data is often
re-allocated.

Therefore, we need once again to go over armature objects and invalidate
their posebone pointers.

This should also be back-ported to Blender LTS 2.83.

Maniphest Tasks: T80078

Differential Revision: https://developer.blender.org/D8734