message: Fix integer abs -> TMath::Abs AliCentralitySelectionTask
  Code is good as is, but generates warning.
diff: @@ -1841,7 +1841,7 @@ void AliCentralitySelectionTask::UserExec(Option_t */*option*/)
  }
  - if ((fMB) && (abs(zvtx)<10)) fHOutMultCL1vsTKL->Fill(spdCorr,nTracklets);
  + if ((fMB) && (TMath::Abs(zvtx)<10)) fHOutMultCL1vsTKL->Fill(spdCorr,nTracklets);
  if (fCVHN) fHOutCentV0MCVHN->Fill(fCentV0M);
  if (fCVLN) fHOutCentV0MCVLN->Fill(fCentV0M);
  