make test: automatic "vpp finishes startup" check

Add code which checks if vpp doesn't crash/exit immediately after
startup to aid debugging stuff like mistyped graph node name or so.
Refuse to run tests if the vpp is unable to start, complain loudly
and print vpp's stderr at critical log level if this happens to make
spotting these problems in jenkins easy.

Change-Id: I40d3fbd05c822c0534713bae6bef05ecfb0e0c1d
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/sanity_run_vpp.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+from framework import VppTestCase
+from hook import VppDiedError
+from sys import exit
+
+
+class SanityTestCase(VppTestCase):
+    """ Dummy test case used to check if VPP is able to start """
+    pass
+
+if __name__ == '__main__':
+    rc = 0
+    tc = SanityTestCase
+    try:
+        tc.setUpClass()
+    except VppDiedError:
+        rc = -1
+    else:
+        try:
+            tc.tearDownClass()
+        except:
+            pass
+
+    exit(rc)