Fix bug in marshal where bad data would cause a segfault due to
lack of an infinite recursion check.

Contributed by Damien Miller at Google.
diff --git a/Misc/ACKS b/Misc/ACKS
index 7524bae..58dab22 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -413,6 +413,7 @@
 Greg McFarlane
 Michael McLay
 Gordon McMillan
+Damien Miller
 Jay T. Miller
 Chris McDonough
 Andrew McNamara