//usage: "[-q] <[-dn] DIR | -x DEVICE>"
//usage:#define mountpoint_full_usage "\n\n"
//usage: "Check if the directory is a mountpoint\n"
-//usage: "\nOptions:"
//usage: "\n -q Quiet"
//usage: "\n -d Print major/minor device number of the filesystem"
//usage: "\n -n Print device name of the filesystem"