Fix namespace builds with -no-qml-debug

Task-number: QTBUG-65924
Change-Id: I47b3afbb8235900156c814874d5ae2250cf13da8
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/qml/debugger/qqmlprofiler_p.h

@@ -452,7 +452,12 @@ private:
     QQmlProfiler *profiler;
 };
 
+#endif // QT_NO_QML_DEBUGGER
+
 QT_END_NAMESPACE
+
+#ifndef QT_NO_QML_DEBUGGER
+
 Q_DECLARE_METATYPE(QVector<QQmlProfilerData>)
 Q_DECLARE_METATYPE(QQmlProfiler::LocationHash)