gnu: ghostscript: Replace with 9.22 [security fixes].

Fixes CVE-2017-{7948,7975,8908,9216,9610,9611,9612,9618,9619,9620,9726,9727,
9739,9740,9835}.

* gnu/packages/ghostscript.scm (ghostscript)[replacement]: New field.
(ghostscript-9.22): New variables.

gnu/packages/ghostscript.scm

@@ -131,6 +131,7 @@ printing, and psresize, for adjusting page sizes.")
 (define-public ghostscript
   (package
     (name "ghostscript")
+    (replacement ghostscript-9.22)
     (version "9.21")
     (source
       (origin
@@ -254,6 +255,25 @@ output file formats and printers.")
     (home-page "https://www.ghostscript.com/")
     (license license:agpl3+)))
 
+(define ghostscript-9.22
+  (package
+    (inherit ghostscript)
+    (version "9.22")
+    (source
+      (origin
+        (inherit (package-source ghostscript))
+        (uri (string-append "https://github.com/ArtifexSoftware/"
+                            "ghostpdl-downloads/releases/download/gs"
+                            (string-delete #\. version)
+                            "/ghostscript-" version ".tar.xz"))
+        (sha256
+         (base32
+          "1fyi4yvdj39bjgs10klr31cda1fbx1ar7a7b7yz7v68gykk65y61"))
+        (patches (search-patches "ghostscript-runpath.patch"
+                                 "ghostscript-no-header-creationdate.patch"
+                                 "ghostscript-no-header-id.patch"
+                                 "ghostscript-no-header-uuid.patch"))))))
+
 (define-public ghostscript/x
   (package/inherit ghostscript
     (name (string-append (package-name ghostscript) "-with-x"))