[PATCH v2] osutil: add darwin-only version of os.listdir using cffi

[Jun Wu]

The cdef(packed=True) feature has been in pypy since 2.4 years ago:
https://bitbucket.org/pypy/pypy/commits/8d8d72389794

And I can confirm it exists in pypy 5.3.1.

Excerpts from Maciej Fijalkowski's message of 2016-07-18 13:10:07 +0200:
> I found a way around  it, but I would vastly prefer not to rely on
> features that would require e.g. not-yet-released version of pypy