bug#25077: 25.1; Incorrect Edebug spec for c-lang-defvar

[Gemini Lasswell <gazally@runbox.com>]

The Edebug spec for c-lang-defvar doesn't allow for the use of
'dont-doc, which prevents the use of Edebug and Testcover on
cc-langs.el.

To reproduce, using emacs -Q starting at the root of the Emacs
sources:

M-: (require 'cc-langs) RET
C-x C-f lisp/progmodes/cc-langs.el RET
C-s dont-doc RET
C-u C-M-x

Result: edebug-syntax-error: Invalid read syntax: stringp, "failed"

I tried this change to the Edebug spec for c-lang-defvar, and it makes
Edebug work on all the c-lang-defvar uses in this file:

(def-edebug-spec c-lang-defvar
  (&define name def-form &optional &or ("quote" "dont-doc") stringp))
  
Alternatively, the 'dont-doc could be removed from the 7 places it is
used. The majority of c-lang-defvar calls simply omit the docstring,
and the code in c-lang-defvar is not doing any checking for dont-doc,
it simply ignores that parameter if it is not a string.


In GNU Emacs 25.1.1 (x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G1004))
 of 2016-10-09 built on rainbow.local
Windowing system distributor 'Apple', version 10.3.1404
Configured using:
 'configure --disable-dependency-tracking --disable-silent-rules
 --enable-locallisppath=/usr/local/share/emacs/site-lisp
 --infodir=/usr/local/Cellar/emacs/25.1/share/info/emacs
 --prefix=/usr/local/Cellar/emacs/25.1 --without-x --with-xml2
 --without-dbus --with-gnutls --with-imagemagick --with-rsvg --with-ns
 --disable-ns-self-contained'

Configured features:
JPEG RSVG IMAGEMAGICK NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS
NS

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
  diff-auto-refine-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
cc-langs
Mark saved where search started
edebug-syntax-error: Invalid read syntax: stringp, "failed"

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns help-mode mail-prsvr
mail-utils edebug misearch multi-isearch vc-git diff-mode easymenu
easy-mmode cc-langs cc-vars cc-defs cl-loaddefs pcase cl-lib time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel ns-win ucs-normalize term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list newcomment elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame
cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai
tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian
slovak czech european ethiopic indian cyrillic chinese charscript
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote kqueue cocoa ns
multi-tty make-network-process emacs)

Memory information:
((conses 16 213456 7451)
 (symbols 48 21513 0)
 (miscs 40 56 248)
 (strings 32 20403 6753)
 (string-bytes 1 591046)
 (vectors 16 35188)
 (vector-slots 8 670702 4578)
 (floats 8 164 167)
 (intervals 56 443 37)
 (buffers 976 18))