QDnsTlsAssociationRecord: Use the PURE_SWAP macro for move-assign

Found in API-review.

Change-Id: I77aecfdf31a2a3507798faa03f24f3ea26bf8173
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit 7e7b7eb37e780d5c43ba291d4f88d29f4b31d403)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/network/kernel/qdnslookup.h

@@ -193,7 +193,7 @@ public:
     QDnsTlsAssociationRecord(QDnsTlsAssociationRecord &&other)
         : d(std::move(other.d))
     {}
-    QDnsTlsAssociationRecord &operator=(QDnsTlsAssociationRecord &&other) noexcept { swap(other); return *this; }
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QDnsTlsAssociationRecord)
     QDnsTlsAssociationRecord &operator=(const QDnsTlsAssociationRecord &other);
     ~QDnsTlsAssociationRecord();