gnu: gdk-pixbuf: Replace with 2.36.10.

Fixes CVE-2017-2862, CVE-2017-2870 and CVE-2017-6311.

* gnu/packages/gtk.scm (gdk-pixbuf, gdk-pixbuf+svg)[replacement]: New field.
(gdk-pixbuf-2.36.10, gdk-pixbuf+svg-2.36.10): New variables.

gnu/packages/gtk.scm

@@ -427,6 +427,7 @@ highlighting and other features typical of a source code editor.")
 (define-public gdk-pixbuf
   (package
    (name "gdk-pixbuf")
+   (replacement gdk-pixbuf-2.36.10)
    (version "2.36.6")
    (source (origin
             (method url-fetch)
@@ -483,6 +484,7 @@ in the GNOME project.")
 (define-public gdk-pixbuf+svg
   (package (inherit gdk-pixbuf)
     (name "gdk-pixbuf+svg")
+    (replacement gdk-pixbuf+svg-2.36.10)
     (inputs
      `(("librsvg" ,librsvg)
        ,@(package-inputs gdk-pixbuf)))
@@ -506,6 +508,26 @@ in the GNOME project.")
     (synopsis
      "GNOME image loading and manipulation library, with SVG support")))
 
+;; Graft replacement packages to fix these vulnerabilities.
+;; https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-2862
+;; https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-2870
+;; https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-6311
+(define-public gdk-pixbuf-2.36.10
+  (package (inherit gdk-pixbuf)
+           (version "2.36.A")
+           (source (origin
+                     (method url-fetch)
+                     (uri (string-append "mirror://gnome/sources/gdk-pixbuf/2.36/"
+                                         "gdk-pixbuf-2.36.10.tar.xz"))
+                     (sha256
+                      (base32
+                       "1klsjkdbashd8yb8xjsc9ff3bz32n2id5s79nrrmqiw9df4zmxpq"))))))
+
+(define-public gdk-pixbuf+svg-2.36.10
+  (package (inherit gdk-pixbuf+svg)
+           (version "2.36.A")
+           (source (origin (inherit (package-source gdk-pixbuf-2.36.10))))))
+
 (define-public at-spi2-core
   (package
    (name "at-spi2-core")