Jasper St. Pierre authored Nov 01, 2012 and Peter Hutterer committed Dec 17, 2012

In order to send events to specific windows associated with the barrier,
we need to move the code that handles barriers to somewhere where it's
easier to construct and send events. Rather than duplicating XSync with
its XSyncSelectAlarm, re-use the existing XI infrastructure.

For now, just move a bunch of code over, rename some things, and initialize
the new structures, but still consider it a separate codebase. Pointer barrier
requests are still handled by XFixes, so this is a weird intermediate state.
It's unknown whether we'll add explicit requests to pointer barriers inside
XI.

Signed-off-by: Jasper St. Pierre <jstpierre@mecheye.net>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>