licenses: Add 'imlib2'.

* guix/licenses.scm (imlib2): New variable.
* gnu/packages/image.scm (imlib2): Use it.

gnu/packages/image.scm

@@ -313,9 +313,7 @@ without sacrificing speed.
 
 This is a complete rewrite over the Imlib 1.x series.  The architecture is
 more modular, simple, and flexible.")
-    ;; This license adds several sentences to the original X11 license.
-    (license (license:x11-style "file://COPYING"
-                                "See 'COPYING' in the distribution."))))
+    (license license:imlib2)))
 
 (define-public giblib
   (package

guix/licenses.scm

@@ -37,6 +37,7 @@
             isc
             ijg
             ibmpl1.0
+            imlib2
             lgpl2.0 lgpl2.0+ lgpl2.1 lgpl2.1+ lgpl3 lgpl3+
             mpl2.0
             openldap2.8 openssl
@@ -195,6 +196,11 @@ which may be a file:// URI pointing the package's tree."
            "http://directory.fsf.org/wiki/License:IBMPLv1.0"
            "https://www.gnu.org/licenses/license-list#IBMPL"))
 
+(define imlib2
+  (license "Imlib2"
+           "http://directory.fsf.org/wiki/License:Imlib2"
+           "https://www.gnu.org/licenses/license-list#imlib"))
+
 (define lgpl2.0
   (license "LGPL 2.0"
            "https://www.gnu.org/licenses/old-licenses/lgpl-2.0.html"