TrigConfigSvc: Fix gcc8 compilation warnings.

gcc8 compilation warnings: catching polymorphic exceptions via value.

Trigger/TrigConfiguration/TrigConfigSvc/src/HLTConfigSvc.cxx

@@ -337,7 +337,7 @@ TrigConf::HLTConfigSvc::queryInterface( const InterfaceID& riid, void** ppvIF )
          try {
             *ppvIF = dynamic_cast<IHLTConfigSvc*>( this );
          }
-         catch( std::bad_cast ) {
+         catch( const std::bad_cast& ) {
             return StatusCode::FAILURE;
          }
          sc = StatusCode::SUCCESS;

Trigger/TrigConfiguration/TrigConfigSvc/src/LVL1ConfigSvc.cxx

@@ -201,7 +201,7 @@ LVL1ConfigSvc::queryInterface( const InterfaceID& riid, void** ppvIF ) {
       if( riid == ILVL1ConfigSvc::interfaceID() ) {
          try {
             *ppvIF = dynamic_cast<ILVL1ConfigSvc*>( this );
-         } catch( bad_cast ) {
+         } catch( const bad_cast& ) {
             return StatusCode::FAILURE;
          }
          sc = StatusCode::SUCCESS;