ProjectWindow: Do not listen for Kit updates during shutdown

The SessionManager is disconnected at that point already, so we were
never told that projects were destructed already and were happily
calling into those.

This fixes the crash described in QTCREATORBUG-10354.

Task-number: QTCREATORBUG-10354
Change-Id: Ib8ce07d6db38dbff9154b127f5fb620a9961c742
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/projectexplorer/projectwindow.cpp

@@ -273,6 +273,7 @@ void ProjectWindow::aboutToShutdown()
 {
     showProperties(-1, -1); // that's a bit stupid, but otherwise stuff is still
                             // connected to the session
+    disconnect(KitManager::instance(), 0, this, 0);
     disconnect(SessionManager::instance(), 0, this, 0);
 }