QRestReply: use qt_ptr_swap instead of std::swap

qt_ptr_swap is our swap compile-time optimizer. It's faster because it
hardcodes noexcept(true) and std::swap() must calculate it.

Amends 9ba5c7ff6a.

Pick-to: 6.7
Change-Id: I1b5a326276bd30638ac9b6dcf597abb5e53ada00
Reviewed-by: Juha Vuolle <juha.vuolle@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/access/qrestreply.h

@@ -35,7 +35,7 @@ public:
     void swap(QRestReply &other) noexcept
     {
         wrapped.swap(other.wrapped);
-        std::swap(d, other.d);
+        qt_ptr_swap(d, other.d);
     }
 
     Q_NETWORK_EXPORT QNetworkReply *networkReply() const;