workaround for valgrind error reported as ATLASRECTS-4769

As discussed in yesterday's reconstruction meeting I added code to ignore tracks that would otherwise create the 'conditional-jump' error reported as ATLASRECTS-4769. I added WARNING that is fired surprisingly often. So a better fix might be worth a thought.

• Walter

Reconstruction/RecoTools/TrackToCalo/src/ParticleCaloCellAssociationTool.cxx

@@ -93,6 +93,9 @@ namespace Rec {
       auto pos2 = pos;
       if(sample== CaloSampling::PreSamplerB) {
         pos2 = entryExitLayerMap.find(CaloSampling::EMB1);
+	if (pos2==entryExitLayerMap.end()) {
+	    pos2=pos;
+	  }
       } 
       //// calculate 3D path length
       double path = 0.;