Remove (unused) in-kernel event filtering, it's currently dead code.

Remove (unused) in-kernel event filtering, it's currently dead code.

All events are currently exported to userland in order to support complex
filters.  If this becomes a bottleneck it should be possible to translate
(some) user-land filters to in-kernel fitlers.

Prodded by a diff from Christian Ludwig to also trace the tracing program.

ok claudio@