cosmetic: vty_test_runner.py: add comment for vim auto settings

Change-Id: I61a0476a0317b011432bb4f6f593cfdcaf1c072b
diff --git a/openbsc/tests/vty_test_runner.py b/openbsc/tests/vty_test_runner.py
index 00eae70..9fe4c3e 100644
--- a/openbsc/tests/vty_test_runner.py
+++ b/openbsc/tests/vty_test_runner.py
@@ -1338,3 +1338,5 @@
     add_sgsn_test(suite, workdir)
     res = unittest.TextTestRunner(verbosity=verbose_level).run(suite)
     sys.exit(len(res.errors) + len(res.failures))
+
+# vim: set shiftwidth=4 expandtab nocin ai