SDL: cleanup and add patch to discover extensions

pkgs/development/libraries/SDL_sound/default.nix

@@ -1,7 +1,8 @@
-{stdenv, fetchurl, SDL, libvorbis, flac, libmikmod}:
+{ stdenv, fetchurl, SDL, libvorbis, flac, libmikmod }:
 
 stdenv.mkDerivation rec {
-  name = "SDL_sound-1.0.3";
+  name = "SDL_sound-${version}";
+  version = "1.0.3";
 
   src = fetchurl {
     url = "http://icculus.org/SDL_sound/downloads/${name}.tar.gz";
@@ -10,10 +11,10 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ SDL libvorbis flac libmikmod ];
 
-  postInstall = "ln -s $out/include/SDL/SDL_sound.h $out/include/";
-
-  meta = {
+  meta = with stdenv.lib; {
     description = "SDL sound library";
-    platforms = stdenv.lib.platforms.linux;
+    platforms = platforms.linux;
+    license = licenses.lgpl21;
+    homepage = "https://www.icculus.org/SDL_sound/";
   };
 }