Fixes #3776 - allowing state loss when closing dialog while stopping activity

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

src/main/java/com/owncloud/android/ui/activity/UploadFilesActivity.java

@@ -707,7 +707,7 @@ public class UploadFilesActivity extends FileActivity implements
     @Override
     protected void onStop() {
         if (dialog != null) {
-            dialog.dismiss();
+            dialog.dismissAllowingStateLoss();
         }
 
         super.onStop();