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/NEWS b/Misc/NEWS
index 1b3e1d9..eefa181 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -207,6 +207,9 @@
 Library
 -------
 
+- Fix bug in marshal where bad data would cause a segfault due to
+  lack of an infinite recursion check.
+
 - Removed plat-freebsd2 and plat-freebsd3 directories (and IN.py in
   the directories).