Add some virtual destructors to remove the compiling warnings

git-svn-id: svn://bind10.isc.org/svn/bind10/branches/trac356@3706 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/nsas/hash_deleter.h

@@ -46,6 +46,10 @@ public:
     HashDeleter(HashTable<T>& hashtable) : hashtable_(hashtable)
     {}
 
+    /// \brief Destructor
+    ///
+    virtual ~HashDeleter(){}
+
     // The default copy constructor and assignment operator are correct for
     // this object.
 

src/lib/nsas/hash_table.h

@@ -89,6 +89,11 @@ HashTableSlot<T>::HashTableSlot(const HashTableSlot<T>& unused UNUSED_PARAM) :
 template <typename T>
 class HashTableCompare {
 public:
+    /// \brief Constructor
+    HashTableCompare(){}
+
+    /// \brief virtual Destructor
+    virtual ~HashTableCompare() {}
 
     /// \brief Comparison Function
     ///
@@ -144,6 +149,10 @@ public:
     /// in BIND-9 for its address database.
     HashTable(HashTableCompare<T>* cmp, uint32_t size = 1009);
 
+    /// \brief Destructor
+    ///
+    virtual ~HashTable(){}
+
     /// \brief Get Entry
     ///
     /// Returns a shared_ptr object pointing to the table entry

src/lib/nsas/lru_list.h

@@ -59,6 +59,11 @@ public:
     /// will handle any additional operations needed.
     class Dropped {
     public:
+        /// \brief Constructor
+        Dropped(){}
+
+        /// \brief Virtual Destructor
+        virtual ~Dropped(){}
 
         /// \brief Dropped Object Handler
         ///