Sync snapshots tools with pkgbox64's current.
manpages - Bring VOP_FSYNC(9) up to date
manpages - Bring VOP_ACCESS(9) up to date
tools - Fix backup file permissions for hammer-backup.sh

- Make sure backup files are only readable by root
- Fix typo in a comment
- Set /usr/sbin as the default installation directory
manpages: Fix a couple things left behind on the previous commit