CaloEvent: Clang fix.

The previous root workaround change causes a problem with clang, which
doesn't seem to properly implement __attribute__((used)) for destructors.
For clang, move the destructor completely out-of-line.  (Trying to remove
the destructor entirely resulted in a mysterious crash in TClass...).


Former-commit-id: 806825294b5df121673c2a2dc78a5519e036e565

Calorimeter/CaloEvent/CaloEvent/CaloClusterMomentStore.h

 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef CALOEVENT_CALOCLUSTERMOMENTSTORE_H
@@ -59,7 +59,11 @@ class CaloClusterMomentStore
       CaloClusterMomentIterator(moment_store_const_iter iStore)
 	ATH_CLING_BODY (: m_actual(iStore) { } )
       /*! \brief Destructor */
+#ifdef __clang__
+      ~CaloClusterMomentIterator();
+#else
       ~CaloClusterMomentIterator() ATH_CLING_BODY( { } )
+#endif
 
       /*! \brief Iterator advance method */
       CaloClusterMomentIterator next()

Calorimeter/CaloEvent/src/CaloClusterMomentStore.cxx

 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2018 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -68,3 +68,8 @@ bool CaloClusterMomentStore::retrieveMomentTypes(moment_type_list&
     } 
   return oldSize < rMomList.size();
 }
+
+
+#ifdef __clang__
+CaloClusterMomentStore::CaloClusterMomentIterator::~CaloClusterMomentIterator() {}
+#endif