Mark QDBusError::ErrorType a Q_ENUM

Easier qDebugging.

Fixes: QTBUG-77183
Change-Id: Ife213d861bb14c1787e1fffd15b63a1f8d64cc30
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/dbus/qdbuserror.h

@@ -41,6 +41,7 @@
 #define QDBUSERROR_H
 
 #include <QtDBus/qtdbusglobal.h>
+#include <QtCore/qobjectdefs.h>
 #include <QtCore/qstring.h>
 
 #ifndef QT_NO_DBUS
@@ -54,6 +55,7 @@ class QDBusMessage;
 
 class Q_DBUS_EXPORT QDBusError
 {
+    Q_GADGET
 public:
     enum ErrorType {
         NoError = 0,
@@ -90,6 +92,7 @@ public:
         LastErrorType = InvalidMember
 #endif
     };
+    Q_ENUM(ErrorType)
 
     QDBusError();
 #ifndef QT_BOOTSTRAPPED