Fix wrong "added on" date

This only happens for magnet links when its metadata has yet to be retrieved.
Closes #11124.

src/base/bittorrent/torrenthandle.h

@@ -36,6 +36,7 @@
 #include <libtorrent/torrent_handle.hpp>
 #include <libtorrent/torrent_status.hpp>
 
+#include <QDateTime>
 #include <QHash>
 #include <QObject>
 #include <QQueue>
@@ -83,6 +84,7 @@ namespace BitTorrent
         int downloadLimit;
         // for new torrents
         QVector<DownloadPriority> filePriorities;
+        QDateTime addedTime;
         // for restored torrents
         qreal ratioLimit;
         int seedingTimeLimit;