Fix undefined __syspal reference

There is no such reference AFAICT. Use SystemPalette instead.

Task-number: QTBUG-41390
Change-Id: I09becb9a39e20137a5092942c4d9cb09ef133abb
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>

examples/quick/controls/calendar/qml/main.qml

@@ -54,6 +54,10 @@ ApplicationWindow {
 
     title: "Calendar Example"
 
+    SystemPalette {
+        id: systemPalette
+    }
+
     SqlEventModel {
         id: eventModel
     }
@@ -77,7 +81,7 @@ ApplicationWindow {
             style: CalendarStyle {
                 dayDelegate: Item {
                     readonly property color sameMonthDateTextColor: "#444"
-                    readonly property color selectedDateColor: Qt.platform.os === "osx" ? "#3778d0" : __syspal.highlight
+                    readonly property color selectedDateColor: Qt.platform.os === "osx" ? "#3778d0" : systemPalette.highlight
                     readonly property color selectedDateTextColor: "white"
                     readonly property color differentMonthDateTextColor: "#bbb"
                     readonly property color invalidDatecolor: "#dddddd"