perf session: Make ordered_events reusable

ordered_events__free() leaves linked lists and timestamps not cleared,
so unable to be reused after ordered_events__free(). Which is inconvenient
after 'perf record' supports generating multiple perf.data output and
process build-ids for each of them.

Use ordered_events__reinit() for this.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1460535673-159866-2-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
[ Split from larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -1836,7 +1836,11 @@ out:
 out_err:
 	ui_progress__finish();
 	perf_session__warn_about_errors(session);
-	ordered_events__free(&session->ordered_events);
+	/*
+	 * We may switching perf.data output, make ordered_events
+	 * reusable.
+	 */
+	ordered_events__reinit(&session->ordered_events);
 	auxtrace__free_events(session);
 	session->one_mmap = false;
 	return err;