This adds support for clients that would like to get a notification
every time a barrier is hit, and allows clients to temporarily release
a barrier so that pointers can go through them, without having to
destroy and recreate barriers.
Based on work by Chris Halse Rogers <chris.halse.rogers@canonical.com>
Signed-off-by: Jasper St. Pierre <jstpierre@mecheye.net>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
e130a46ab4