I propose to drop freebsd support from these packages (moby/sys/mount and moby/sys/mountinfo)

Pros:

• it is not being tested and I'm not sure it's working
• it is not used by moby/moby, and might not have any users at all
• mountinfo for freebsd requires cgo (for getmntinfo(3))

Cons:

• it might still being used by someone