Hmm I think a better way is what you suggested stopping it from compiling by creating a build.rs checking for the current OS and running a panic, although hmmm this will only address freebsd and not other supported platforms. Will have to think about that.

I updated #289 with some info about FreeBSD's Linux compat layer, that does allow FreeBSD users to run Linux binaries directly, and enables the use of bob on FreeBSD simply by installing/enabling 2 additional items.

For the first proposed approach to fix, it wouldn't require changing the cfg test tree at all, and would just be a single log warning the user of the requirements and pointing to the FreeBSD Handbook.

I can rework this MR to that later today if you like the approach.

I like this newer approach

Push. Also patched a couple lints that seemed to be blocking pipelines.