artiq/test/{not,harness}.py: usual CLI handling

artiq/test/harness.py

@@ -11,6 +11,7 @@ emulate the same behavior when invoked under lit.
 
 import sys, os, argparse, importlib
 
+def main():
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('-m', metavar='mod', type=str,
                         help='run library module as a script')
@@ -29,3 +30,6 @@ else:
         with open(args.args[0]) as f:
             code = compile(f.read(), args.args[0], 'exec')
             exec(code)
+
+if __name__ == "__main__":
+    main()

artiq/test/not.py

@@ -1,2 +1,7 @@
 import sys, subprocess
+
+def main():
     exit(not subprocess.call(sys.argv[1:]))
+
+if __name__ == "__main__":
+    main()