- text-based mount command: make po_rightmost() work for N options
    - text-based mount command: Function to stuff "struct pmap" from mount
        options
    - text-based mount options: Use new pmap stuffer when rewriting mount
        options
    - text-based mount command: fix mount option rewriting logic
    - text-based mount command: support AF_INET6 in rewrite_mount_options()