Use the new plugin system

Change-Id: Ibd3a5870945fcd2d78e0f2c8282f34f1bebd54b2
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@nokia.com>

src/qstyleplugin.cpp

@@ -94,5 +94,3 @@ void StylePlugin::initializeEngine(QQmlEngine *engine, const char *uri)
     Q_UNUSED(uri);
     engine->addImageProvider("desktoptheme", new DesktopIconProvider);
 }
-
-Q_EXPORT_PLUGIN2(styleplugin, StylePlugin);

src/qstyleplugin.h

@@ -49,6 +49,7 @@
 class StylePlugin : public QQmlExtensionPlugin
 {
     Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.playground.qtdesktopcomponents.QQmlExtensionInterface" FILE "styleplugin.json")
 public:
     void registerTypes(const char *uri);
     void initializeEngine(QQmlEngine *engine, const char *uri);

src/styleplugin.json

+{}