Enable setresuid and setresgid for more platforms

[wezm]

unistd::setresuid and unistd::setresgid are currently wrapped in a module that only is only included on Linux and Android. The functions appear to be present on other systems as well:

• FreeBSD
• OpenBSD

NetBSD and macOS don't appear to have them.

[Susurrus]

Would you be will in to file a PR enabling them on those platforms? You'll need the check that they're all defined in libc beforehand so everything will pass CI.

[wezm]

Yep definitely. Will aim to do it this week.

[Susurrus]

@wezm Excellent, thanks for being willing to contribute! In the future, feel free to just file a PR instead of both an issue and a PR, unless you're uncertain if we'd accept the feature. It generates slightly less noise for us maintainers :-)

[wezm]

Ok, no problem, will do. Turns out neither of these functions are in the libc crate (for FreeBSD and OpenBSD). So I'll have to do the dance of getting them added there first.

[Susurrus]

@wezm Excellent, thanks. If you could add it for all supported platforms also, so we can offer pretty complete support here in nix, it'd be much appreciated. When you create an issue, please link it to this one so I can track progress.

[jlgerber]

What about OS X?