fix a bunch of Coverity FORWARD_NULL issues

proof/pq2/src/pq2actions.cxx

proof/proof/src/TDataSetManager.cxx

proof/proof/src/TDataSetManagerFile.cxx

proof/proof/src/TProof.cxx

proof/proof/src/TProofCondor.cxx

proof/proof/src/TProofLite.cxx

proof/proof/src/TProofResourcesStatic.cxx

proof/proof/src/TProofServ.cxx

proof/proof/src/TProofSuperMaster.cxx

proof/proof/src/TSlave.cxx

proof/proofplayer/src/TEventIter.cxx

proof/proofplayer/src/TOutputListSelectorDataMap.cxx

proof/proofplayer/src/TPacketizer.cxx

proof/proofplayer/src/TPerfStats.cxx

proof/proofplayer/src/TProofPlayer.cxx