requested to merge asturmlechner/qtbase:asturmlechner/QTBUG-78737-QSystemTrayIcon-disconnect-oldmenu into kde/5.15
Amends 121a30cc Fix the unfortunate mistake where oldMenu was not properly disconnected from the contextMenuRequested() signal. This could lead to a situation when several menus are displayed at the same time.
Note: 5.15 codereview not even submitted yet upstream, but cherry-pick is straightforward.
See also: https://bugreports.qt.io/browse/QTBUG-78737