Address code review

Author: corona10

Include/internal/pycore_dict.h

@@ -111,7 +111,6 @@ extern void _PyDictKeys_DecRef(PyDictKeysObject *keys);
  * -1 when no entry found, -3 when compare raises error.
  */
 extern Py_ssize_t _Py_dict_lookup(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **value_addr);
-extern Py_ssize_t _Py_frozendict_lookup(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **value_addr);
 extern Py_ssize_t _Py_dict_lookup_threadsafe(PyDictObject *mp, PyObject *key, Py_hash_t hash, PyObject **value_addr);
 extern Py_ssize_t _Py_dict_lookup_threadsafe_stackref(PyDictObject *mp, PyObject *key, Py_hash_t hash, _PyStackRef *value_addr);