QFileDialog: compile with QT_NO_URL_CAST_FROM_STRING.

This is useful to detect confusions between local paths and URLs.

Change-Id: I1aa72ae10186984812691c8a1a4e843db3c85246
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

src/widgets/dialogs/qfiledialog.cpp

@@ -39,6 +39,8 @@
 **
 ****************************************************************************/
 
+#define QT_NO_URL_CAST_FROM_STRING
+
 #include <qvariant.h>
 #include <private/qwidgetitemdata_p.h>
 #include "qfiledialog.h"

src/widgets/dialogs/qfiledialog_p.h

@@ -369,7 +369,7 @@ inline QUrl QFileDialogPrivate::directory_sys() const
 {
     if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
         return helper->directory();
-    return QString();
+    return QUrl();
 }
 
 inline void QFileDialogPrivate::selectFile_sys(const QUrl &filename)