Fix crash: click the Remember-menu works again
Fix crash: click the Remember-menu works again

This commit fixes a subtle regression introduced by myself in
f64727ca: WinClient wc = FbMenu::window()->winclient() creates a
copy and this copy gets cleaned up at the end of the scope. What
I really wanted was a reference.

luebking/fluxbox,luebking/fluxbox,Arkq/fluxbox,olivergondza/fluxbox,naimdjon/fluxbox,luebking/fluxbox,Arkq/fluxbox,Arkq/fluxbox,Arkq/fluxbox,lukoko/fluxbox,naimdjon/fluxbox,lukoko/fluxbox,lukoko/fluxbox,olivergondza/fluxbox,naimdjon/fluxbox,lukoko/fluxbox,luebking/fluxbox,olivergondza/fluxbox,Arkq/fluxbox,lukoko/fluxbox,luebking/fluxbox,naimdjon/fluxbox,olivergondza/fluxbox,olivergondza/fluxbox,naimdjon/fluxbox