QArrayDataPointer: use move and swap in move assignment

Not plain swap; QADP does not hold just memory but arbitrary
state (depending on T).

Change-Id: I3560577e4109607a51b2c72b67e22e38813977b3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qarraydatapointer.h

@@ -103,7 +103,8 @@ public:
 
     QArrayDataPointer &operator=(QArrayDataPointer &&other) noexcept
     {
-        this->swap(other);
+        QArrayDataPointer moved(std::move(other));
+        swap(moved);
         return *this;
     }