QDirIterator, QDataStream: remove virtual dtor

These two classes are not meant to be polymorphic,
and have no other other virtual functions besides
the destructor, so remove the overhead of the
vtable completely.

Change-Id: I08b93898312c2fbbe4db92d4f1c444c6417fe19a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/corelib/io/qdatastream.h

@@ -114,7 +114,7 @@ public:
     explicit QDataStream(QIODevice *);
     QDataStream(QByteArray *, QIODevice::OpenMode flags);
     QDataStream(const QByteArray &);
-    virtual ~QDataStream();
+    ~QDataStream();
 
     QIODevice *device() const;
     void setDevice(QIODevice *);

src/corelib/io/qdiriterator.h

@@ -70,7 +70,7 @@ public:
                  QDir::Filters filters = QDir::NoFilter,
                  IteratorFlags flags = NoIteratorFlags);
 
-    virtual ~QDirIterator();
+    ~QDirIterator();
 
     QString next();
     bool hasNext() const;