Replace goo.gl style link

That URL shortening scheme should stop working soon [1], while we
don't really need it here.

1. https://developers.googleblog.com/en/google-url-shortener-links-will-no-longer-be-available/

Signed-off-by:  Alexander Motin <mav@FreeBSD.org>

tests/test-runner/bin/test-runner.py.in

@@ -111,7 +111,7 @@ class Result(object):
 class Output(object):
     """
     This class is a slightly modified version of the 'Stream' class found
-    here: http://goo.gl/aSGfv
+    here: https://stackoverflow.com/q/4984549/
     """
     def __init__(self, stream, debug=False):
         self.stream = stream