stubgen (stubgenc): Support for tp_getset style C properties

Feature

Currently for C extensions, attributes of a C type originating from tp_getset are not recognized as a class property.
It would be nice to still parse the docstring in such cases, to infer types.

Pitch

As far as I understand, this is due to mypy.stubgenc.is_c_property looking for the fget attribute (the tp_getset style attributes dont have such an attribute - at least in my case, python 3.8).

I am not sure how to properly add checks for such a case (is just removing the check hasattr(obj, 'fget') enough?)

Would be glad for any input here (Am I missing something? Is there a good strategy to add support for tp_getset style attributes?). I would offer to implement the feature, if you think this would make sense.

Beginne bei mypy.stubgenc.is_c_property und untersuche, wie stubgen Eigenschaften erkennt und ihre Docstrings liest. Ermittle, wie sich C-Attribute im Stil von tp_getset vom bestehenden Fall unterscheiden, und überprüfe anschließend, dass ihre Docstrings zur Ableitung von Eigenschaftstypen verwendet werden können, ohne andere Attribute von C-Erweiterungen zu beeinflussen.