QmlProfiler: manage server-side start tracing message

also
QmlProfiler: refactor eventlist state

If unexpected data is received, assuming server stopped profiling.
Also, introducing a eventlist state instead of relying on
signals sent around.  This is part of a coming bigger patch
where the profiler client is refactored.

Change-Id: Ibed9007903956daf03cc0fcb90f77b5ad2d3cf90
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

src/plugins/qmlprofiler/qml/Overview.qml

@@ -77,8 +77,9 @@ Canvas2D {
 
     Connections {
         target: qmlEventList
-        onDataReady: {
-            if (qmlEventList.count() > 0) {
+        onStateChanged: {
+            // State is "done"
+            if (qmlEventList.getCurrentStateFromQml() == 3) {
                 dataAvailable = true;
                 requestRedraw();
             }