Fix clang warnings.
Fix overloaded-virtual warnings.
Fix overloaded-virtual warnings.
Fix overloaded-virtual warnings.
Fix overloaded-virtual warnings.
Merge pull request #3877 from alja/clang-71w

Clang -- 71x:: fix overloaded-virtual warnings
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X