Remove an unneeded assignment.

Found using Clang's static analyzer.

Objects/typeobject.c

@@ -971,7 +971,7 @@ subtype_dealloc(PyObject *self)
 
 	/*  Clear slots up to the nearest base with a different tp_dealloc */
 	base = type;
-	while ((basedealloc = base->tp_dealloc) == subtype_dealloc) {
+	while (base->tp_dealloc == subtype_dealloc) {
 		if (Py_SIZE(base))
 			clear_slots(base, self);
 		base = base->tp_base;