SGSN: prevent starting with inconsistent config

Previously it was possible to start osmo-sgsn with "auth-policy remote"
but without "gsup remote-*" which resulted in broken setup: no MS could
perform GPRS ATTACH. Add consistency check to vty code to fix this.

Related: OS#1582
Change-Id: Ie4296e7d99d7833f7d828b0196435ea81097cf6e
diff --git a/openbsc/tests/vty_test_runner.py b/openbsc/tests/vty_test_runner.py
index 23939e8..00eae70 100644
--- a/openbsc/tests/vty_test_runner.py
+++ b/openbsc/tests/vty_test_runner.py
@@ -1086,6 +1086,8 @@
         self.assertTrue(self.vty.verify('auth-policy closed', ['']))
         res = self.vty.command("show running-config")
         self.assert_(res.find('auth-policy closed') > 0)
+        self.assertTrue(self.vty.verify('gsup remote-ip 127.0.0.4', ['']))
+        self.assertTrue(self.vty.verify('gsup remote-port 2222', ['']))
         self.assertTrue(self.vty.verify('auth-policy remote', ['']))
         res = self.vty.command("show running-config")
         self.assert_(res.find('auth-policy remote') > 0)