license: Add giftware.

* guix/licenses.scm (giftware): New variable.

guix/licenses.scm

@@ -40,6 +40,7 @@
             epl1.0
             expat
             freetype
+            giftware
             gpl1 gpl1+ gpl2 gpl2+ gpl3 gpl3+
             gfl1.0
             fdl1.3+
@@ -201,6 +202,11 @@ at URI, which may be a file:// URI pointing the package's tree."
            "http://directory.fsf.org/wiki/License:Freetype"
            "https://www.gnu.org/licenses/license-list.html#freetype"))
 
+(define giftware
+  (license "Giftware"
+           "http://liballeg.org/license.html"
+           "The Allegro 4 license"))
+
 (define gpl1
   (license "GPL 1"
            "https://www.gnu.org/licenses/old-licenses/gpl-1.0.html"