When maximizing a window, the previous location is saved so that
un-maximize would restore the same original window location.
However, if a Wayland client starts with a window maximized, the
previous location will be 0x0, so if we have to force placement in
xdg_toplevel_set_maximized(), we should update the location as well so
that the window is placed on the right monitor when un-maximizing.
For that purpose, add a new flag to force the update of the window
location, and use that flag from xdg_toplevel_set_maximized().
https://bugzilla.gnome.org/show_bug.cgi?id=783901