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 9ba5c7ff6aa42c5701cf950d2137467a2d178833.

Change-Id: I1b5a326276bd30638ac9b6dcf597abb5e53ada00
Reviewed-by: Juha Vuolle <juha.vuolle@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit f70e113b2e895fb71db4ee6fb77a91f65e2deae9)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

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;