8297435: Remove unused CompactibleSpaceClosure

Reviewed-by: dholmes

Author: albertnetymk

src/hotspot/share/memory/iterator.hpp

@@ -233,13 +233,6 @@ class SpaceClosure : public StackObj {
   virtual void do_space(Space* s) = 0;
 };
 
-class CompactibleSpaceClosure : public StackObj {
- public:
-  // Called for each compactible space
-  virtual void do_space(CompactibleSpace* s) = 0;
-};
-
-
 // CodeBlobClosure is used for iterating through code blobs
 // in the code cache or on thread stacks