(ps-lpr-switches, ps-lpr-command): Just setq them;

(ps-lpr-switches, ps-lpr-command): Just setq them;
duplicate defvar is a bad idea.

(dos-printer): New variable, the local printer device.
(dos-print-region-function): New function, used for `print-region-function'.
(dos-ps-printer): New variable; if a string, it's the name of the
local printer device.
(ps-lpr-command, ps-lpr-switches): Set them properly for Ghostscript.
(lpr-headers-switches): Set to non-nil, to disable page headers'
support under MS-DOS.