Use add/remove-function to manipulate process-filters.

Use add/remove-function to manipulate process-filters.
* lisp/emacs-lisp/nadvice.el (advice--where-alist): Add :override.
(remove-function): Autoload.

* lisp/comint.el (comint-redirect-original-filter-function): Remove.
(comint-redirect-cleanup, comint-redirect-send-command-to-process):
* lisp/vc/vc-cvs.el (vc-cvs-annotate-process-filter,vc-cvs-annotate-command):
* lisp/progmodes/octave-inf.el (inferior-octave-send-list-and-digest):
* lisp/progmodes/prolog.el (prolog-consult-compile):
* lisp/progmodes/gdb-mi.el (gdb, gdb--check-interpreter):
Use add/remove-function instead.
* lisp/progmodes/gud.el (gud-tooltip-original-filter): Remove.
(gud-tooltip-process-output, gud-tooltip-tips):
Use add/remove-function instead.
* lisp/progmodes/xscheme.el (xscheme-previous-process-state): Remove.
(scheme-interaction-mode, exit-scheme-interaction-mode):
Use add/remove-function instead.

* lisp/vc/vc-dispatcher.el: Use lexical-binding.
(vc--process-sentinel): Rename from vc-process-sentinel.
Change last arg to be the code to run.  Don't use vc-previous-sentinel
and vc-sentinel-commands any more.
(vc-exec-after): Allow code to be a function.  Use add/remove-function.
(compilation-error-regexp-alist, view-old-buffer-read-only): Declare.