[PATCH] perf tools: fix missing default initialization for tool->mmap2

[Stephane Eranian <eranian@google.com>]

This patch fixes a SEGFAULT bug with perf sched
related to the new MMAP2 record type. There was
a missing default initialization for the tool->mmap2
pointer in perf_tool__fill_defaults().

Reproducer:
 # perf sched record -- sleep 1
 # perf sched lat

Reported-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Stephane Eranian <eranian@google.com>
--

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 211b325..8415c54 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -256,6 +256,8 @@ void perf_tool__fill_defaults(struct perf_tool *tool)
 		tool->sample = process_event_sample_stub;
 	if (tool->mmap == NULL)
 		tool->mmap = process_event_stub;
+	if (tool->mmap2 == NULL)
+		tool->mmap2 = process_event_stub;
 	if (tool->comm == NULL)
 		tool->comm = process_event_stub;
 	if (tool->fork == NULL)