TrigT1CaloCalibTools: DataVector const fix

A long-standing DataVector bug has allowed getting a non-const pointer
from a const_iterator.  Fix a const problem in this package that relied
on this bug.

Trigger/TrigT1/TrigT1CaloCalibTools/src/L1CaloLArTowerEnergy.cxx

@@ -99,7 +99,7 @@ namespace LVL1{
 
     mapSum::iterator it_map;
 
-    LVL1::TriggerTower *tt;
+    const LVL1::TriggerTower *tt;
     TriggerTowerCollection::const_iterator p_itTT = triggerTowerCollection.begin();
     TriggerTowerCollection::const_iterator p_itTTEnd = triggerTowerCollection.end();