Remove CLHEP external dependency
This merge request removes the external linking to the CLHEP package, so that the code will use the internal Geant4 CLHEP built version. This will avoid hidden versions conflicts that may arise.
This merge request removes the external linking to the CLHEP package, so that the code will use the internal Geant4 CLHEP built version. This will avoid hidden versions conflicts that may arise.