Fix issue #3547: ctypes is confused by bitfields of varying integer types

Reviewed by Fredrik Lundh and Skip Montanaro.

Backport from trunk.
diff --git a/Misc/NEWS b/Misc/NEWS
index a4c2ef5..1a58dba 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -86,6 +86,9 @@
 Library
 -------
 
+- Issue #3547: Fixed ctypes structures bitfields of varying integer
+  sizes.
+
 - Issue #3762: platform.architecture() fails if python is lanched via
   its symbolic link.