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/PC/_subprocess.c b/PC/_subprocess.c
index 8c9a352..99cbd24 100644
--- a/PC/_subprocess.c
+++ b/PC/_subprocess.c
@@ -133,7 +133,7 @@
 	0, /*tp_print*/
 	0,				/*tp_getattr*/
 	0,				/*tp_setattr*/
-	0,				/*tp_compare*/
+	0,				/*tp_reserved*/
 	0,				/*tp_repr*/
 	&sp_handle_as_number,		/*tp_as_number */
 	0,				/*tp_as_sequence */