When the compositor unmaximized the window, we get a
state-changed signal, and we update the maximized field.
But then we go and recompute our layout based on the
maximize_initially field, and that is still TRUE, when
we were maximized initially. So we need to update both
fields.

This fixes a problem where using the window menu to
unmaximize an initially maximized window would not
work.

Fixes: #3226