QmlProfiler: Handle enable and show signals for zoomslider in C++

As it's hard to pass arguments for signals from non-QML-mapped objects
to QML objects handle the signal in C++ instead and just directly set
the properties.

Task-number: QTCREATORBUG-10943
Change-Id: I039f6938db3d7e64ca1a4bcff2f0f6aa79c65219
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/qmlprofiler/qmlprofilertraceview.h

@@ -102,6 +102,8 @@ private slots:
     void profilerStateChanged();
     void clientRecordingChanged();
     void serverRecordingChanged();
+    void setZoomSliderEnabled(bool enabled);
+    void setZoomSliderVisible(bool visible);
 
 signals:
     void gotoSourceLocation(const QString &fileUrl, int lineNumber, int columNumber);