Add freebsd nmount

[DarcInc]

Adding FreeBSD's nmount call to mount devices on filesystems. nmount is preferred over mount.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @JohnTitor (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[JohnTitor]

Note that CI for FreeBSD 10 is currently broken, it should be fixed in a few days. The change itself looks good, r=me once you squash commits into one or two (nmount and fdatasync) and CI works fine again.

[DarcInc]

Rgr. @JohnTitor Squashed and redelivered.

[JohnTitor]

Thanks!

[JohnTitor]

@bors r+

[bors]

📌 Commit 16e0a0b has been approved by JohnTitor

[bors]

⌛ Testing commit 16e0a0b with merge 40e0d54...

[bors]

☀️ Test successful - checks-actions, checks-cirrus-freebsd-11, checks-cirrus-freebsd-12, checks-cirrus-freebsd-13
Approved by: JohnTitor
Pushing 40e0d54 to master...