Check if the filters are different before triggering an update

If the filters list is the same as before, then there is no reason to
trigger an update on the thread as the result would be the same as
before. This solves a problem that was occurring with iOS 13 as it would
get stuck due to repeated calls to setNameFilters() with the same
filter list.

Fixes: QTBUG-78468
Change-Id: I705cfaaa0a1a19b1d0397140a5831fc67557a4ee
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

src/imports/folderlistmodel/qquickfolderlistmodel.cpp

@@ -539,6 +539,8 @@ QStringList QQuickFolderListModel::nameFilters() const
 void QQuickFolderListModel::setNameFilters(const QStringList &filters)
 {
     Q_D(QQuickFolderListModel);
+    if (d->nameFilters == filters)
+        return;
     d->fileInfoThread.setNameFilters(filters);
     d->nameFilters = filters;
 }