[NFC][emacs] remove out-of-date comment from tablegen-mode.el

[inglorion]

Summary

The syntax table was originally based on and attributed to
jasmin.el, but was rewritten in r45192, so the comment that
says the code comes from jasmin.el is no longer accurate. This
change removes the comment, shortening the code a bit.

[MaskRay]

If you decide to rewrite the file, just combine these changes...

llvm/utils/emacs/tablegen-mode.el

;;     '("\/\/" . font-lock-comment-face)
      kw
      ;; Type keywords
      type-kw
      ))
   "Additional expressions to highlight in TableGen mode.")
 (put 'tablegen-mode 'font-lock-defaults '(tablegen-font-lock-keywords))
 
 ;; ---------------------- Syntax table ---------------------------
-;; Shamelessly ripped from jasmin.el
-;; URL: http://www.neilvandyke.org/jasmin-emacs/jasmin.el
 
 (defvar tablegen-mode-syntax-table nil
   "Syntax table used in `tablegen-mode' buffers.")
 (when (not tablegen-mode-syntax-table)
   (setq tablegen-mode-syntax-table (make-syntax-table))
   ;; whitespace (` ')
   (modify-syntax-entry ?\   " "      tablegen-mode-syntax-table)
   (modify-syntax-entry ?\t  " "      tablegen-mode-syntax-table)