Replace PyObject_CallFunctionObjArgs() with fastcall

* PyObject_CallFunctionObjArgs(func, NULL) => _PyObject_CallNoArg(func)
* PyObject_CallFunctionObjArgs(func, arg, NULL) => _PyObject_CallArg1(func, arg)

PyObject_CallFunctionObjArgs() allocates 40 bytes on the C stack and requires
extra work to "parse" C arguments to build a C array of PyObject*.

_PyObject_CallNoArg() and _PyObject_CallArg1() are simpler and don't allocate
memory on the C stack.

This change is part of the fastcall project. The change on listsort() is
related to the issue #23507.

Python/_warnings.c

@@ -415,7 +415,7 @@ call_show_warning(PyObject *category, PyObject *text, PyObject *message,
     if (msg == NULL)
         goto error;
 
-    res = PyObject_CallFunctionObjArgs(show_fn, msg, NULL);
+    res = _PyObject_CallArg1(show_fn, msg);
     Py_DECREF(show_fn);
     Py_DECREF(msg);