Don't warn when calling hl-lock-mode from init file

Don't warn when calling hl-lock-mode from init file

This was a compatibility kluge introduced in Emacs 22.1, twenty years
ago.  It's fair to assume that any former Emacs 21 user have seen this
warning already, and will have updated their init file.  So remove it.

* lisp/hi-lock.el (hi-lock-mode): Don't warn when calling plain
hi-lock-mode from init file.
(hi-lock-archaic-interface-message-used)
(hi-lock-archaic-interface-deduce): Remove associated variables.

(cherry picked from commit fad9b7dce73d81d669cb22f880b65c867ac36b54)