replace PyXXX_Length calls with PyXXX_Size calls
diff --git a/Modules/cStringIO.c b/Modules/cStringIO.c
index 4c187fe..321e79b 100644
--- a/Modules/cStringIO.c
+++ b/Modules/cStringIO.c
@@ -367,7 +367,7 @@
     Py_DECREF(string_module);
   }
 
-  if (PyObject_Length(args) == -1) {
+  if (PyObject_Size(args) == -1) {
     return NULL;
   }