We now move (and so, arrange) windows anywhen so we need to ignore
spurious leaver/enter events in client_resize() too.
We still need it un arrange for unmap/map. It's probably that the call
to client_ignore_enterleave_events() should be made in client_ban, but
it would be too much expansive to call it outside arrange() since it is
the only caller of client_ban/unban.
Signed-off-by: Julien Danjou <julien@danjou.info>