QCoreApplicationPrivate: make the type member 8 bits

So it packs better with the booleans around it.

Change-Id: I330164b99fcbbf9e9629fffd52bcbb38bec4ac0e
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
(cherry picked from commit ede95ef7e916ffb946878477938c304a5dc206d3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qcoreapplication_p.h

@@ -51,7 +51,7 @@ class Q_CORE_EXPORT QCoreApplicationPrivate
     Q_DECLARE_PUBLIC(QCoreApplication)
 
 public:
-    enum Type {
+    enum Type : quint8 {
         Tty,
         Gui
     };