perf session: Skip event correctly for unknown id/machine

In case the perf_session__process_event function fails, we estimate the
next event offset.

This is not necessary for sample event failing on unknown ID or machine.
In such case we know proper size of the event, so we dont need to guess.
Also failure statistics are updated correctly so we don't miss any
information.

Forcing perf_session__process_event to return 0 in case of unknown ID or
machine.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1334233262-5679-3-git-send-email-jolsa@redhat.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>