alsa: setup mirrors for src downloads (#41761)

This commit adds a list of supported mirrors for all alsa projects, as described
on the download section of the alsa-project hompage:
http://alsa-project.org/main/index.php/Download

pkgs/os-specific/linux/alsa-utils/default.nix

@@ -5,10 +5,7 @@ stdenv.mkDerivation rec {
   version = "1.1.6";
 
   src = fetchurl {
-    urls = [
-      "ftp://ftp.alsa-project.org/pub/utils/${name}.tar.bz2"
-      "http://alsa.cybermirror.org/utils/${name}.tar.bz2"
-    ];
+    url = "mirror://alsa/utils/${name}.tar.bz2";
     sha256 = "0vnkyymgwj9rfdb11nvab30dnfrylmakdfildxl0y8mj836awp0m";
   };
 
@@ -27,7 +24,6 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = http://www.alsa-project.org/;
     description = "ALSA, the Advanced Linux Sound Architecture utils";
-
     longDescription = ''
       The Advanced Linux Sound Architecture (ALSA) provides audio and
       MIDI functionality to the Linux-based operating system.