src/hotspot/share/gc/parallel/psCompactionManager.hpp

8224665: Parallel GC: Use WorkGang (7: remove task manager)

   friend class ParMarkBitMap;
   friend class PSParallelCompact;
   friend class CompactionWithStealingTask;
   friend class UpdateAndFillClosure;
   friend class RefProcTaskExecutor;
-  friend class IdleGCTask;
   friend class PCRefProcTask;
   friend class MarkFromRootsTask;
   friend class UpdateDensePrefixAndCompactionTask;
 
  public: