Redox uses `;` as separators in these files, and doesn't have the
"password" flag in `/etc/group`. With these, it seems to parse fine.

I didn't think it'd be this useful first, but thank god for `cargo fix --edition`!

- Remove incorrect header styles
- Use export.replace where header style was previously needed
- Check compilation of tests using system gcc

This stops configure scripts from identifying them as valid