Some Linux packages (shakes fist angrily at Java) look to see if `/proc` is mounted as a part of the installation by running
`mountpoint /proc`
While the Linux jail can see the contents of its `/proc` directory, the linprocfs driver will not generate the correct contents for `/proc/mounts` or `/proc/self/mountinfo` as `kern_getfsstat()` will, by default, filter all mount points other than the jail's chroot directory.
Fix is to set `enforce_statfs` to allow mount points below the jail's chroot directory to be visible.
abc8a6b280