Don't grab stat mutex for final stat output

We should not need it, and there's a bug with getting stuck on it
that hasn't been fully debugged/understood yet. So for now, lets
just forget about the mutex for final output.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/stat.c b/stat.c
index d836581..89d7194 100644
--- a/stat.c
+++ b/stat.c
@@ -1169,7 +1169,7 @@
 	ts->groupid = -1;
 }
 
-static void __show_run_stats(void)
+void __show_run_stats(void)
 {
 	struct group_run_stats *runstats, *rs;
 	struct thread_data *td;