QmlProfiler: Make sure y-offset in category labels is an integer

This is only a workaround, for older versions of Qt. The real bug is
that a non-integer y offset is interpreted inconsistently by QtQuick.

Task-number: QTCREATORBUG-11732
Change-Id: Idcad0bf0cbef58b41c45e38aa29596717523ed0b
Reviewed-by: Christian Stenger <christian.stenger@digia.com>

src/plugins/qmlprofiler/qml/CategoryLabel.qml

@@ -144,7 +144,7 @@ Item {
     Image {
         source: expanded ? "arrow_down.png" : "arrow_right.png"
         x: parent.width - 12
-        y: root.singleRowHeight / 2 - height / 2
+        y: Math.floor((root.singleRowHeight - height) / 2)
         smooth: false
         MouseArea {
             anchors.fill: parent