7019689: Non-dependent name is found in dependent base class although it should be rejected

Summary: fix hashtable.hpp to qualify non-dependant name with "this"
Reviewed-by: phh, never, poonam
Contributed-by: volker.simonis@gmail.com

src/share/vm/utilities/hashtable.hpp

@@ -276,7 +276,7 @@ public:
   }
 
   int index_for(Symbol* name, Handle loader) {
-    return hash_to_index(compute_hash(name, loader));
+    return this->hash_to_index(compute_hash(name, loader));
   }
 };