made the resolving level volatile in case a class is used from multiple threads
made the resolving level volatile in case a class is used from multiple threads

mbenz89/soot,anddann/soot,plast-lab/soot,mbenz89/soot,anddann/soot,mbenz89/soot,plast-lab/soot,plast-lab/soot,anddann/soot,mbenz89/soot,anddann/soot