Some arch implementations call perf_event_overflow() by 'accident',
ignore this.
Reported-by: NFrancis Moreau <francis.moro@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>