Improve diaglib.

- Fix prototype for glinfo() for Qt 4
- Add more event types and object type flags to event filter.

Change-Id: Ia4160b40486d054e860a339e7b5c9c28695330ae
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Andy Shaw <andy.shaw@digia.com>