gnu: Add prefix to license imports in (gnu packages imagemagick).

* gnu/packages/imagemagick.scm: Import (guix licenses) with prefix
  "license:".

gnu/packages/imagemagick.scm

@@ -22,7 +22,7 @@ (define-module (gnu packages imagemagick)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system perl)
   #:use-module (guix download)
-  #:use-module ((guix licenses) #:select (fsf-free))
+  #:use-module ((guix licenses) #:prefix license:)
   #:use-module (gnu packages)
   #:use-module (gnu packages algebra)
   #:use-module (gnu packages compression)
@@ -104,7 +104,7 @@ (define-public imagemagick
 and TIFF.  Use ImageMagick to resize, flip, mirror, rotate, distort, shear and
 transform images, adjust image colors, apply various special effects, or draw
 text, lines, polygons, ellipses and Bézier curves.")
-    (license (fsf-free "http://www.imagemagick.org/script/license.php"))))
+    (license (license:fsf-free "http://www.imagemagick.org/script/license.php"))))
 
 (define-public perl-image-magick
   (package