Compile with refactor

Change-Id: I248f811a13ca00ccbf5d342a556d389bca625856
Reviewed-on: http://codereview.qt-project.org/4940
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

examples/spectrum/app/app.pro

@@ -90,3 +90,4 @@ macx {
 }
 
 
+QT+=widgets

examples/spectrum/app/main.cpp

@@ -38,7 +38,7 @@
 **
 ****************************************************************************/
 
-#include <QtGui/QApplication>
+#include <QtWidgets/QApplication>
 #include "mainwidget.h"
 
 int main(int argc, char **argv)