Issue #1717: rename tp_compare to tp_reserved.  I'll change the
type of tp_compare in a separate commit, for ease of reversion
should things go wrong.
diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index 2294500..e5c6c7d 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -320,7 +320,7 @@
     0,                          /*tp_print*/
     0,                          /*tp_getattr*/
     0,                          /*tp_setattr*/
-    0,                          /* tp_compare; */
+    0,                          /* tp_reserved; */
     (reprfunc)BaseException_repr, /*tp_repr*/
     0,                          /*tp_as_number*/
     0,                          /*tp_as_sequence*/