Example: Enable auto scaling on HighDPI screens

Task-number: QTBUG-56425
Change-Id: I2246245216fb8cd0d4dc4b15a0687edfc64ccad1
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

examples/quick/shared/shared.h

@@ -44,6 +44,7 @@
 #include <QQuickView> //Not using QQmlApplicationEngine because many examples don't have a Window{}
 #define DECLARATIVE_EXAMPLE_MAIN(NAME) int main(int argc, char* argv[]) \
 {\
+    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);\
     QGuiApplication app(argc,argv);\
     app.setOrganizationName("QtProject");\
     app.setOrganizationDomain("qt-project.org");\