ctypes callback functions only support 'fundamental' result types.
Check this and raise an error when something else is used - before
this change ctypes would hang or crash when such a callback was
called.  This is a partial fix for #1574584.

Will backport to release25-maint.
diff --git a/Misc/NEWS b/Misc/NEWS
index 9d22aed..b0f8f55 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -81,6 +81,10 @@
 Library
 -------
 
+- ctypes callback functions only support 'fundamental' data types as
+  result type.  Raise an error when something else is used.  This is a
+  partial fix for Bug #1574584.
+
 - Fix turtle so that time.sleep is imported for the entire library.  Allows
   the demo2 function to be executed on its own instead of only when the
   module is run as a script.