being output if <= 1 rpos; there is a bug in the kernel which doesn't
quite get along with this. Changed default #rpos to 1, and fixed up
manual page. Converted nrpos to 1 if user specifies 0.
the use of the rotational position table.
2) Allow specification of 0 rotational positions (disables function).
3) Make rotdelay=0 and nrpos=0 by default.
The purpose of the above is to optimize for modern SCSI (and IDE) drives
that do read-ahead/write-behind.
