Integer overflow in _json_encode_unicode leads to crash

sp = "\x13"*715827883 #((2**32)/6 + 1) json.dumps([sp], ensure_ascii=False)

# static PyObject *
# escape_unicode(PyObject *pystr)
# {
#     /* Take a PyUnicode pystr and return a new escaped PyUnicode */
#     Py_ssize_t i;
#     Py_ssize_t input_chars;
#     Py_ssize_t output_size;
#     Py_ssize_t chars;
#     PyObject *rval;
#     void *input;
#     int kind;
# …