present: Only send PresentCompleteNotify events to the presenting client

We were sending the events to all clients listening for them on the
window. But clients can get confused by events from another client, and
I can't imagine any case where receiving events from other clients would
be required.

v2:
* Also restrict events sent to additional windows to the presenting
  client
* Don't shorten line lengths

Reviewed-by: Keith Packard <keithp@keithp.com>
(cherry picked from commit 559954aa)