Add more support for POSIX 1003.1-2001, which requires removal for

Add more support for POSIX 1003.1-2001, which requires removal for
support of obsolete "-N" option syntax in expand, head, fold,
split, tail, unexpand, uniq, and which prohibits options with
optional arguments in od and pr.

(usage): Document this.
(main): Check for obsolete options.
(shortopts): New constant.
(main): Use -1, not EOF, for getopt_long.