Nuke nix

[Jake-Shadle]

I noticed #114 (comment) when I was looking to see why the 0.8.1 version of this crate is using an older version of nix so figured removing nix would be fine. This crate has constantly been using slightly older versions of nix from other dependencies we use, and when I went to replace the use of nix found that the usage was incredibly minimal.

I only tested on linux and had the same test failures as before this change so don't think I broke anything, but I wasn't sure what the intended support for BSD-like targets is since this crate doesn't seem to state anything about them or have CI for them, but I did add support for them, though I failed to figure out to actually get eg. freebsd to build via cross.

[diwic]

Hi and thanks a lot for the PR!

I think the whole picture makes sense. A few questions:

1. Are you the owner of this code or are you copy/pasting it from some other project? Just to make sure there are no accidental license violations here.

2. I understand this will be a backwards incompatible change, is there a short summary of what a user is supposed to change during the upgrade?

[Jake-Shadle]

1. No, the code was mostly copied piecemeal from nix, which is MIT licensed so I didn't think it would be problematic.
2. The only public change is that nix is no longer re-exported, so crates that depend on alsa that just use the re-export instead of their own dependency on nix would need to change, and the methods to retrieve the nix error directly are gone so if a crate was doing a direct conversion from the nix error to their own error type that would need to change.

[diwic]

Okay, cool. Let's add comments on the bigger things you copy-pasted from nix so we leave a little credit. Then squash all commits into one and I think we're ready for merge.

[diwic]

...assuming all cargo tests still run fine, that is.

[diwic]

...and it's in!

Assuming you want an alsa 0.9 release with this code in it, are there any other dependencies I should update before I go ahead and release a 0.9?

[Jake-Shadle]

Thanks! Nope, I don't believe so, libc has been 0.2 for forever and this crate already uses the latest bitflags, it was only nix that was the issue.

[diwic]

Released now, enjoy!

[Jake-Shadle]

Thanks for the quick turnaround!