Fixed thread safety compiler warnings in package...
requested to merge atsirigo/athena:Fix-thread-safety-warnings-in-MuonLinearSegmentMakerUtilities_ATLASRECTS-5288 into master
Fixed thread safety compiler warnings in package MuonLinearSegmentMakerUtilities. These were coming from ClusterAnalysis class which it had many static pointers declared. Made them unique_ptr class members. Also, fixed messaging.