freebsd: include missing libc crate

[Drakulix]

This causes compilation issues with the libc references in the devname_r definition in the devname function. With this compiling on freebsd succeeds.

Also make the non-linux versions of dev_path public, so other OS types can call it.

[Drakulix]

@amshafer Given this is an edition 2021 crate, we shouldn't need the extern crate and yes, I would like to limit the dependency to freebsd.

I pushed a new commit, that should already include all these changes, can you confirm, that this also fixes the problem for you? cargo check --target x86_64-unknown-freebsd seems to agree on my system, but I don't wanna setup a cross-compiler or VM or properly test this small change, if not necessary.

If so, I can merge this and do a patch release quickly.

[amshafer]

Thanks, can confirm this does still fix the issue.

[Drakulix]

Should be published as 0.14.1