[Twisted-Python] OS X and setup.py

[Andrew Bennetts]

This part of setup.py is breaking build_ext on OS X (which doesn't have
poll):

if os.name == "posix":
    setup_args['ext_modules'].append(
        Extension("twisted.internet.cReactor",
              glob('twisted/internet/cReactor/*.c'),
              define_macros=define_macros))
    
That's from the bottom of setup.py.  It completely ignores the
_detect_modules thing.  It reports "The C reactor is unavailable on this
system" -- then tries to build it anyway.  Disabling that code fragment
fixes the problem.

A comment suggests that code is needed to make sdist work... would someone
like to figure out how to make this work correctly?

-Andrew.