TrackToCalo: Configuration fix.

It's wrong to throw away a CA and just return an algorithm --- should
return the CA instead.

See ATLASRECTS-5726.

Reconstruction/RecoTools/TrackToCalo/python/CaloExtensionBuilderAlgCfg.py

-# Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+# Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 from AthenaConfiguration.ComponentFactory import CompFactory
 
-def getCaloExtenstionBuilderAlgorithm(inputFlags):
+def CaloExtensionBuilderAlgCfg(inputFlags):
     from TrkConfig.AtlasExtrapolatorConfig import AtlasExtrapolatorCfg    
     Trk__ParticleCaloExtensionTool = CompFactory.Trk.ParticleCaloExtensionTool
-    extrapPFlowCfg = AtlasExtrapolatorCfg(inputFlags)
-    pcExtensionTool = Trk__ParticleCaloExtensionTool(Extrapolator = extrapPFlowCfg.popPrivateTools())
+    result = AtlasExtrapolatorCfg(inputFlags)
+    pcExtensionTool = Trk__ParticleCaloExtensionTool(Extrapolator = result.popPrivateTools())
         
     CaloExtensionBuilderAlg = CompFactory.Trk.CaloExtensionBuilderAlg 
     CaloExtensionBuilderAlg = CaloExtensionBuilderAlg(LastCaloExtentionTool = pcExtensionTool)
+    result.addEventAlgo (CaloExtensionBuilderAlg)
      
-    return CaloExtensionBuilderAlg
+    return result