gnu: Add allegro-5.0.

* gnu/packages/game-development.scm (allegro-5.0): New variable.

gnu/packages/game-development.scm

@@ -383,6 +383,18 @@ etc.")
     (home-page "http://liballeg.org")
     (license license:bsd-3)))
 
+(define-public allegro-5.0
+  (package (inherit allegro)
+    (name "allegro")
+    (version "5.0.11")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "http://download.gna.org/allegro/allegro/"
+                                  version "/allegro-" version ".tar.gz"))
+              (sha256
+               (base32
+                "0cd51qrh97jrr0xdmnivqgwljpmizg8pixsgvc4blqqlaz4i9zj9"))))))
+
 (define-public aseprite
   (package
     (name "aseprite")