Virtual function calls of the for Foo::bar() are not linked to their override functions, but foo.bar() and foo->bar() are
clear map before each event is processed
same problem in TkConvValidator
Merge pull request #4248 from gartung/clangSA-better-virtual-linkage

Virtual function calls of the for Foo::bar() are not linked to their override
Merge pull request #4253 from davidlange6/remove_hoarding_of_simTracks

clear map before each event is processed in PhotonMCTruthFinder
Merged hltRun2Updates from repository perrotta
Merged CMSSW_7_2_X from repository cms-sw