Fix inclusion of agenda-archives in search view

* org-agenda.el (org-search-view): Fixed inclusion of agenda-archives
in org-agenda-text-search-extra-files.

org-search-view lacked a local binding for
org-agenda-text-search-extra-files. Thus when pop was called on the
variable, the agenda-archives symbol was removed and subsequent
searches failed to include the archives.

lisp/org-agenda.el

@@ -3444,6 +3444,7 @@ in `org-agenda-text-search-extra-files'."
 		      'mouse-face 'highlight
 		      'help-echo (format "mouse-2 or RET jump to location")))
 	 (full-words org-agenda-search-view-force-full-words)
+	 (org-agenda-text-search-extra-files org-agenda-text-search-extra-files)
 	 regexp rtn rtnall files file pos
 	 marker category tags c neg re boolean
 	 ee txt beg end words regexps+ regexps- hdl-only buffer beg1 str)