Fix seg. fault when accessing `ConstantObject` extra

alsa-project/alsa-python pull request #10 was opened from FrancescoCeruti:

This fixes (#9) a segmentation fault that started happening with python 3.12, changes in the PyLongObject implementation have broken some pointer arithmetic, which, from what I understand, is not necessary.

Probably someone with a better understanding of C should check this :)

I've tested with 3.12, 3.11 and 3.7.

Request URL : https://github.com/alsa-project/alsa-python/pull/10 Patch URL : https://github.com/alsa-project/alsa-python/pull/10.patch Repository URL: https://github.com/alsa-project/alsa-python