Add missing imports used by _dont_test_spawn_and_kill

supervisor/tests/test_process.py

@@ -1,9 +1,12 @@
+import errno
+import os
 import signal
-import unittest
 import sys
-import errno
+import time
+import unittest
 
 from supervisor.compat import Mock, patch, sentinel
+from supervisor.compat import as_bytes
 from supervisor.compat import maxint
 
 from supervisor.tests.base import DummyOptions