Support for musl libc (Alpine Linux)

[jessesuen]

Accessing _LIB.errno on musl libc results in "AttributeError: Symbol not found: errno". For musl libc, changing this to _LIB.err resolves the issue.

[dsoprea]

That's annoying.

Please change it to the following and test:

if getattr(_LIB, 'errno') is not None:
    errno = _LIB.errno
elif getattr(_LIB, 'err') is not None:
    errno = _LIB.err
else:
    raise EnvironmentError("'errno' not found in library")

Thanks for contributing.

[jessesuen]

Updated with your feedback, although getattr() needs a default value or else it will still raise AttributeError.

[dsoprea]

Yep. This is just a more general solution, in the event that other distributions have that same difference.

You tested?

[jessesuen]

Yes, tested in debian:8.5 and alpine:3.4 containers.

[jacobsvante]

Any chance we might see a release with this?