6690928: Use spinning in combination with yields for workstealing termination

Substitute a spin loop for most calls to yield() to reduce the stress on the system.

Reviewed-by: tonyp

hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

@@ -2203,6 +2203,10 @@ void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
                            collection_exit.ticks());
     gc_task_manager()->print_task_time_stamps();
   }
+
+#ifdef TRACESPINNING
+  ParallelTaskTerminator::print_termination_counts();
+#endif
 }
 
 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,