QmlProfiler: Keep an extra time window in ZoomControl

This window is dynamically sized so that no integer overflows can occur
when using it in the timeline view instead of the whole trace time.

Task-number: QTCREATORBUG-11879
Change-Id: Id86faaf614b5f833e47ce26bb859b63eb09e7547
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

src/plugins/qmlprofiler/qmlprofilermodelmanager.h

@@ -84,6 +84,10 @@ public:
     qint64 endTime() const;
     qint64 duration() const;
 
+signals:
+    void startTimeChanged(qint64);
+    void endTimeChanged(qint64);
+
 public slots:
     void clear();
     void setStartTime(qint64 time);