gh-112069: Make PySet_GET_SIZE to be atomic safe.

[corona10]

• Issue: Make set thread-safe in --disable-gil builds #112069

[corona10]

tp_richcompare already set locks for two sets, so making PySet_GET_SIZE to be atomic safe will be enough.

cpython/Objects/setobject.c

Lines 2094 to 2111 in 94444ea

	case Py_EQ:
	if (PySet_GET_SIZE(v) != PySet_GET_SIZE(w))
	Py_RETURN_FALSE;
	if (v->hash != -1 &&
	((PySetObject *)w)->hash != -1 &&
	v->hash != ((PySetObject *)w)->hash)
	Py_RETURN_FALSE;
	return set_issubset(v, w);
	case Py_NE:
	r1 = set_richcompare(v, w, Py_EQ);
	if (r1 == NULL)
	return NULL;
	r2 = PyObject_IsTrue(r1);
	Py_DECREF(r1);
	if (r2 < 0)
	return NULL;
	return PyBool_FromLong(!r2);
	case Py_LE:

FYI, the same thing is applied for PyList_GET_SIZE, too.

cpython/Include/cpython/listobject.h

Lines 30 to 37 in 94444ea

	static inline Py_ssize_t PyList_GET_SIZE(PyObject *op) {
	PyListObject *list = _PyList_CAST(op);
	#ifdef Py_GIL_DISABLED
	return _Py_atomic_load_ssize_relaxed(&(_PyVarObject_CAST(list)->ob_size));
	#else
	return Py_SIZE(list);
	#endif
	}