If an exception is raised and PyInit__multibytecodec() returns NULL,
Python reports properly the exception to the user. There is no need
to crash Python with Py_FatalError().

In ArgumentClinic, value "NULL" should now be used only for unrepresentable default values
(like in the optional third parameter of getattr). "None" should be used if None is accepted
as argument and passing None has the same effect as not passing the argument at all.

Automatically replace
tp_print -> tp_vectorcall_offset
tp_compare -> tp_as_async
tp_reserved -> tp_as_async

Fix also return type for few other functions (clear, releasebuffer).

Fixed the following compiler warning in multibytecodec.c:

    warning C4244: '=': conversion from 'Py_ssize_t'
    to 'unsigned char', possible loss of data

Cast Py_ssize_t to unsigned char: the maximum value is checked
on the previous line.

Previous version was casting to Py_ssize_t incorrectly
and exhibited unexpected behavior on big-endian systems.

This implements getstate and setstate for the cjkcodecs multibyte incremental encoders/decoders, primarily to fix issues with seek/tell.

The encoder getstate/setstate is slightly tricky as the "state" is pending bytes + MultibyteCodec_State but only an integer can be returned. The approach I've taken is to encode this data into a long, similar to how .tell() encodes a "cookie_type" as a long.


https://bugs.python.org/issue33578