perf session: Add storage for seperating event types in report

This patch adds the structures necessary to count each event
type independently in perf report.

Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1267804269-22660-4-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 0de7258..eed1cb8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -70,6 +70,7 @@
 
 	memcpy(self->filename, filename, len);
 	self->threads = RB_ROOT;
+	self->stats_by_id = RB_ROOT;
 	self->last_match = NULL;
 	self->mmap_window = 32;
 	self->cwd = NULL;