8302886: Parallel: Remove unimplemented methods in ParCompactionManager

Reviewed-by: tschatzl

Author: albertnetymk

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

@@ -157,17 +157,8 @@ class ParCompactionManager : public CHeapObj<mtGC> {
 
   ParCompactionManager();
 
-  // Pushes onto the region stack at the given index.  If the
-  // region stack is full,
-  // pushes onto the region overflow stack.
-  static void verify_region_list_empty(uint stack_index);
   ParMarkBitMap* mark_bitmap() { return _mark_bitmap; }
 
-  // void drain_stacks();
-
-  bool should_update();
-  bool should_copy();
-
   // Save for later processing.  Must not fail.
   inline void push(oop obj);
   inline void push_objarray(oop objarray, size_t index);