Delete obsolete variable gnus-secondary-servers

* lisp/gnus/gnus.el (gnus-secondary-servers): Delete variable
obsolete since 24.1.
* lisp/gnus/gnus-group.el (gnus-group-browse-foreign-server):
* lisp/gnus/gnus-int.el (gnus-start-news-server): Don't use above
deleted variable.

etc/NEWS

@@ -2317,8 +2317,9 @@ This change is now applied in 'dired-insert-directory'.
 'font-lock-maximum-size', 'gnus-carpal',
 'gnus-debug-exclude-variables', 'gnus-debug-files',
 'gnus-local-domain', 'gnus-outgoing-message-group',
-'gnus-registry-user-format-function-M', 'image-extension-data',
-'image-library-alist', 'inhibit-first-line-modes-regexps',
+'gnus-secondary-servers', 'gnus-registry-user-format-function-M',
+'image-extension-data', 'image-library-alist',
+'inhibit-first-line-modes-regexps',
 'inhibit-first-line-modes-suffixes', 'intdos',
 'mail-complete-function', 'mail-completion-at-point-function',
 'mail-mailer-swallows-blank-line', 'mail-sent-via', 'make-register',

lisp/gnus/gnus-group.el

@@ -4532,9 +4532,11 @@ and the second element is the address."
 		      ;; FIXME? gnus-secondary-servers is obsolete,
 		      ;; and it is not obvious that there is anything
 		      ;; sensible to use instead in this particular case.
-		      (if (boundp 'gnus-secondary-servers)
-			  gnus-secondary-servers
-			(cdr gnus-select-method))))
+                      ;; (if (boundp 'gnus-secondary-servers)
+                      ;;     gnus-secondary-servers
+                      ;;   (cdr gnus-select-method))
+                      nil
+                      ))
 	     ;; We got a server name.
 	     how)))
    gnus-group-mode)

lisp/gnus/gnus-int.el

@@ -114,10 +114,7 @@ If CONFIRM is non-nil, the user will be asked for an NNTP server."
 	;; Read server name with completion.
 	(setq gnus-nntp-server
 	      (gnus-completing-read "NNTP server"
-                                    (cons gnus-nntp-server
-					  (if (boundp 'gnus-secondary-servers)
-					      gnus-secondary-servers))
-                                    nil gnus-nntp-server)))
+                                    nil nil gnus-nntp-server)))
 
       (when (and gnus-nntp-server
 		 (stringp gnus-nntp-server)

lisp/gnus/gnus.el

@@ -1110,14 +1110,6 @@ that case, just return a fully prefixed name of the group --
 		 sexp
 		 string))
 
-(defcustom gnus-secondary-servers nil
-  "List of NNTP servers that the user can choose between interactively.
-To make Gnus query you for a server, you have to give `gnus' a
-non-numeric prefix - `\\[universal-argument] \\[gnus]', in short."
-  :group 'gnus-server
-  :type '(repeat string))
-(make-obsolete-variable 'gnus-secondary-servers 'gnus-select-method "24.1")
-
 (defcustom gnus-secondary-select-methods nil
   "A list of secondary methods that will be used for reading news.
 This is a list where each element is a complete select method (see