gnu: expat: Replace with 2.1.1 [fixes CVE-2015-1283].

* gnu/packages/xml.scm (expat)[replacement]: New field.
(expat-2.1.1): New variable.

gnu/packages/xml.scm

@@ -4,7 +4,7 @@
 ;;; Copyright © 2015 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2015 Sou Bunnbu <iyzsong@gmail.com>
 ;;; Copyright © 2015 Ricardo Wurmus <rekado@elephly.net>
-;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2015, 2016 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2015 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2015 Raimon Grau <raimonster@gmail.com>
 ;;;
@@ -43,6 +43,7 @@
 
 (define-public expat
   (package
+    (replacement expat-2.1.1)
     (name "expat")
     (version "2.1.0")
     (source (origin
@@ -62,6 +63,20 @@ stream-oriented parser in which an application registers handlers for
 things the parser might find in the XML document (like start tags).")
     (license license:expat)))
 
+(define expat-2.1.1
+  (package
+    (inherit expat)
+    (replacement #f)
+    (source
+     (let ((version "2.1.1"))
+       (origin
+         (method url-fetch)
+         (uri (string-append "mirror://sourceforge/expat/expat/"
+                             version "/expat-" version ".tar.bz2"))
+         (sha256
+          (base32
+           "0ryyjgvy7jq0qb7a9mhc1giy3bzn56aiwrs8dpydqngplbjq9xdg")))))))
+
 (define-public libxml2
   (package
     (name "libxml2")