Q<Typed>Permission: use move-and-swap, not pure-swap, for move-assignment

While PURE_SWAP is the correct one today, this is inline code, so when
we activate the d-pointer, we may have fields that hold non-memory
resources, but it would be too late change existing binary users to
MOVE_AND_SWAP, so do it already now.

Change-Id: I18976cffe30eb4e37aa6d471cc6e75015e9b1ee7
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
(cherry picked from commit c2cdd7c371d7b9405728c1a30046ab3f257ee235)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qpermissions.h

@@ -89,7 +89,7 @@ public: \
         : u{other.u} { other.u.d = nullptr; } \
     Q_CORE_EXPORT ~ClassName(); \
     Q_CORE_EXPORT ClassName &operator=(const ClassName &other) noexcept; \
-    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(ClassName) \
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(ClassName) \
     void swap(ClassName &other) noexcept { std::swap(u, other.u); } \
 private: \
     /*end*/