Use of uninitialized pointer in Argument Clinic generated code

The code generated for the Py_UNICODE converter (and derived converter LPCWSTR) looks like:

const Py_UNICODE *name;
...
if (!_PyArg_ParseXXX(..., name, ...)) {
    goto exit;
}
...
exit:
    PyMem_Free((void *)name);

If parsing fails, PyMem_Free() is called for uninitialized variable.

It is the only converter with non-trivial cleanup which does not have a mandatory initializer.