7096030: G1: PrintGCDetails enhancements 7102445: G1: Unnecessary Resource allocations during RSet scanning Summary: Add a new per-worker thread line in the PrintGCDetails output. GC Worker Other is the difference between the elapsed time for the parallel phase of the evacuation pause and the sum of the times of the sub-phases (external root scanning, mark stack scanning, RSet updating, RSet scanning, object copying, and termination) for that worker. During RSet scanning, stack allocate DirtyCardToOopClosure objects; allocating these in a resource area was causing abnormally high GC Worker Other times while the worker thread freed ResourceArea chunks. Reviewed-by: tonyp, jwilhelm, brutisso