Merge reason: to add event filter support we need the following
commits from the tracing tree:

 3f6fe06d: tracing/filters: Unify the regex parsing helpers
 1889d209: tracing/filters: Provide basic regex support
 737f453f: tracing/filters: Cleanup useless headers
Signed-off-by: NIngo Molnar <mingo@elte.hu>