Fix some compiler warnings.

Mostly about deprecated ASCII casts.

Change-Id: I70428913799c15f20a1a5f80be57848e1072e058
Reviewed-on: http://codereview.qt.nokia.com/4158
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

src/imports/multimedia/multimedia.cpp

@@ -83,6 +83,7 @@ public:
     void initializeEngine(QDeclarativeEngine *engine, const char *uri)
     {
         Q_UNUSED(uri);
+        Q_UNUSED(engine);
 #if 0
         engine->addImageProvider("camera", new QDeclarativeCameraPreviewProvider);
 #endif