gnu: libpeas: Update to 1.12.1, add 'pre-build phase.

* gnu/packages/gnome.scm (libpeas): Update to version 1.12.1 and add
  'pre-build phase.

gnu/packages/gnome.scm

@@ -3,6 +3,7 @@
 ;;; Copyright © 2014 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2014 Ian Denhardt <ian@zenhack.net>
 ;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
+;;; Copyright © 2014, 2015 Federico Beffa <beffa@fbengineering.ch>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -427,7 +428,7 @@ (define-public libnotify
 (define-public libpeas
   (package
     (name "libpeas")
-    (version "1.9.0")
+    (version "1.12.1")
     (source
      (origin
       (method url-fetch)
@@ -436,7 +437,7 @@ (define-public libpeas
                           name "-" version ".tar.xz"))
       (sha256
        (base32
-        "13fzyzv6c0cfdj83z1s16lv8k997wpnzyzr0wfwcfkcmvz64g1q0"))))
+        "1mjjjjwphc83bjznmbsm7x0jg7ql261nys6qnl7mi0nkr4qvw476"))))
     (build-system gnu-build-system)
     (inputs
      `(("atk" ,atk)
@@ -449,6 +450,13 @@ (define-public libpeas
        ("glib:bin" ,glib "bin")
        ("gobject-introspection" ,gobject-introspection)
        ("intltool" ,intltool)))
+    (arguments
+     `(#:phases 
+       (alist-cons-before
+        'build 'pre-build
+        (lambda* _
+          (setenv "CC" "gcc"))
+        %standard-phases)))
     (home-page "https://wiki.gnome.org/Libpeas")
     (synopsis "GObject plugin system")
     (description
@@ -457,7 +465,6 @@ (define-public libpeas
 set of features including, but not limited to: multiple extension points; on
 demand (lazy) programming language support for C, Python and JS; simplicity of
 the API")
-
     (license license:lgpl2.0+)))
 
 (define-public gtkglext