Make platform-indepentent parts of the crate usable on non-Linux platforms

[dralley]

I have a use case that requires validating capabilities strings, that I would like to be able to use on non-Linux operating systems. It seems like all of the capabilities parsing / validating code ought to be platform-independent?

Currently there is no way to do this, the crate won't compile on non-Linux operating systems, and there is no way to disable the platform-specific parts.

There are a few different ways to accomplish this:

• Flag the parts of the library that are strictly Linux-specific as #[cfg(target_os = "linux")] so that other platforms can still use the platform-independent bits.
• Split into sub-crates.
• Use a feature flag

I would be willing to file a PR myself if one of these approaches (probably the first, it seems the least painful) is acceptable.

[dralley]

@cptpcrd Thoughts?

[dralley]

Strangely when I run this on my own GHA CI I seem to get weird failures that aren't at all related to the changes? For instance I removed everything from the PR except for a change that ought to be irrelevant and all the tests failed.

dralley#1