metadatum: remove deleted move operations

These are already deleted. No need to be explicit.

Signed-off-by: Rosen Penev <[email protected]>

Author: neheb

include/exiv2/metadatum.hpp

@@ -33,8 +33,6 @@ class EXIV2API Key {
   //! Destructor
   virtual ~Key();
   //@}
-  Key(Key&&) = delete;
-  Key& operator=(Key&&) = delete;
   //! @name Accessors
   //@{
   /*!