Remove some unused ps-def definitions.

Remove some unused ps-def definitions.

* lisp/ps-def.el (leading-code-private-22, charset-bytes, charset-id)
(charset-width, find-charset-region, chars-in-region, forward-point)
(encode-coding-string, coding-system-p, ccl-execute-on-string)
(define-ccl-program, multibyte-string-p, string-make-multibyte):
Remove compatibility cruft (none of these are used by ps*.el).