message: Fix out-of-bounds access to hits array for MC
  Unprotected access to hits array which triggers out-of-bound
  access in case of too many hits.
diff: @@ -1200,6 +1200,7 @@ void AliTRDmcmSim::AddHitToFitreg(Int_t adc, UShort_t timebin, UShort_t qtot, Sh
  }
  // register hits (MC info)
  + if (fNHits < fgkNHitsMC) {
  fHits[fNHits].fChannel = adc;
  fHits[fNHits].fQtot = qtot;
  fHits[fNHits].fYpos = ypos;
  @@ -1208,6 +1209,9 @@ void AliTRDmcmSim::AddHitToFitreg(Int_t adc, UShort_t timebin, UShort_t qtot, Sh
  fHits[fNHits].fLabel[1] = label[1];
  fHits[fNHits].fLabel[2] = label[2];
  fNHits++;
  + } else {
  + AliWarning("no space left to store MC information for hit");
  + }
  }
  void AliTRDmcmSim::CalcFitreg()
  