Merge branch 'clid.xAODPFlow-20201013' into 'master'

xAODPFlow:  Fix CLID registration.

See merge request atlas/athena!37244

Event/xAOD/xAODPFlow/Root/clids.cxx

+/*
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
+*/
+
+// Ensure that the  headers for the interface classes get included
+// by some object in this library, so that CLID registration will take
+// place properly.
+
+#include "xAODPFlow/FlowElementContainer.h"
+#include "xAODPFlow/PFOContainer.h"
+#include "xAODPFlow/TrackCaloClusterContainer.h"