Issue #12149: Update the method cache after a type's dictionnary gets
cleared by the garbage collector.  This fixes a segfault when an instance
and its type get caught in a reference cycle, and the instance's
deallocator calls one of the methods on the type (e.g. when subclassing
IOBase).

Diagnosis and patch by Davide Rizzo.
diff --git a/Misc/ACKS b/Misc/ACKS
index 45b4042..625317d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -736,6 +736,7 @@
 Nicholas Riley
 Jean-Claude Rimbault
 Juan M. Bello Rivas
+Davide Rizzo
 Anthony Roach
 Mark Roberts
 Jim Robinson