8309761: Leak class loader constraints

Reviewed-by: coleenp, jsjolen

src/hotspot/share/classfile/loaderConstraints.cpp

@@ -89,6 +89,9 @@ class ConstraintSet {                               // copied into hashtable as
   }
 
   ~ConstraintSet() {
+    while (!_constraints->is_empty()) {
+      delete _constraints->pop();
+    }
     delete _constraints;
   }