gnu: emacs-w3m: Fix build.

The previously (unofficial) Git repository mirror is no longer available, so
we fallback to using the official CVS repository.

Fixes issue 33938 (see: https://issues.guix.info/issue/33938).

* gnu/packages/emacs.scm (emacs-w3m)[origin]: Fetch the sources from the
  official CVS repository.

gnu/packages/emacs.scm

@@ -61,6 +61,7 @@
 (define-module (gnu packages emacs)
   #:use-module ((guix licenses) #:prefix license:)
   #:use-module (guix packages)
+  #:use-module (guix cvs-download)
   #:use-module (guix download)
   #:use-module (guix git-download)
   #:use-module (guix gexp)
@@ -843,21 +844,21 @@ index is considered the key).")
 ;;;
 
 (define-public emacs-w3m
-  ;; Emacs-w3m follows a "rolling release" model from its CVS repo.  We could
-  ;; use CVS, sure, but instead we choose to use this Git mirror described on
-  ;; the home page as an "unofficial" mirror.
-  (let ((commit "0dd5691f46d314a84da63f3a7277d721815811a2"))
+  ;; Emacs-w3m follows a "rolling release" model.
   (package
     (name "emacs-w3m")
-      (version (git-version "1.5" "0" commit))
+    (version "2018-11-11")
     (source (origin
-                (method git-fetch)
-                (uri (git-reference
-                      (url "https://github.com/ecbrown/emacs-w3m")
-                      (commit commit)))
+              (method cvs-fetch)
+              (uri (cvs-reference
+                    (root-directory
+                     ":pserver:anonymous@cvs.namazu.org:/storage/cvsroot")
+                    (module "emacs-w3m")
+                    (revision version)))
+              (file-name (string-append name "-" version "-checkout"))
               (sha256
                (base32
-                  "02xalyxbrkgl4n8nj7xxkmsbm6lshhwdc8bzs2l4wz3hkpgkj7x4"))))
+                "0nvahdbjs12zg7zsk4gql02mvnv56cf1rwj2f5p42lwp3xvswiwp"))))
     (build-system gnu-build-system)
     (native-inputs `(("autoconf" ,autoconf)
                      ("texinfo" ,texinfo)
@@ -927,7 +928,7 @@ index is considered the key).")
     (synopsis "Simple Web browser for Emacs based on w3m")
     (description
      "Emacs-w3m is an emacs interface for the w3m web browser.")
-      (license license:gpl2+))))
+    (license license:gpl2+)))
 
 (define-public emacs-wget
   (package