Use eldoc-documentation-functions

Use eldoc-documentation-functions

* lisp/hexl.el (hexl-mode):
* lisp/ielm.el (inferior-emacs-lisp-mode):
* lisp/progmodes/cfengine.el (cfengine3-mode):
* lisp/progmodes/elisp-mode.el (emacs-lisp-mode):
* lisp/progmodes/octave.el (octave-mode, inferior-octave-mode):
* lisp/progmodes/python.el (python-mode):
* lisp/simple.el (read--expression): Add buffer-locally to hook
eldoc-documentation-functions.