perf session: Pass evsel in event_ops->sample()

Resolving the sample->id to an evsel since the most advanced tools,
report and annotate, and the others will too when they evolve to
properly support multi-event perf.data files.

Good also because it does an extra validation, checking that the ID is
valid when present. When that is not the case, the overhead is just a
branch + function call (perf_evlist__id2evsel).

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 0b3c9af..1ac481f 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -55,8 +55,11 @@
 	char			filename[0];
 };
 
+struct perf_evsel;
 struct perf_event_ops;
 
+typedef int (*event_sample)(union perf_event *event, struct perf_sample *sample,
+			    struct perf_evsel *evsel, struct perf_session *session);
 typedef int (*event_op)(union perf_event *self, struct perf_sample *sample,
 			struct perf_session *session);
 typedef int (*event_synth_op)(union perf_event *self,
@@ -65,8 +68,8 @@
 			 struct perf_event_ops *ops);
 
 struct perf_event_ops {
-	event_op	sample,
-			mmap,
+	event_sample	sample;
+	event_op	mmap,
 			comm,
 			fork,
 			exit,