This is the next bit on trying to clean up a bit the thread safety for Tracking Geomety the Builders do not now need to get the input as const so can freely manipulate it.
The previous installments are :
- !56242 (merged) -> removal of un-nneeded const
- !56287 (closed) -> since volumes are not created as const from the start. Now we can manipulate them. TrackingManipulator becomes safe.
- !56293 (closed) -> TrackingVolumeHelper, TrackingVolumeCreator make thread safe.
Until these make it in only the latest commit is relevant (ATLAS-EGamma/athena@fb910ea4)