The core was hooking up relation to a wrong operation, in an
attempt to cause proper full update of the pose (since there
is no intermediate state stored anywhere). This is now done
as a part of flush_handle_component_node(), so can properly
route more granular relation.

This fixes the crash which was caused by an access of partially
evaluated data by solving the fake cycle. However, if there
is a real cycle involved the code will still not survive, but
this is more generic issue (which also includes modifiers
for meshes and curves).