cassandra: use mirrors

Upstream likes to move "old" releases to an archive mirror as soon as a
new one is released. This is now handled for free by mirrors.nix.

(No idea why cs.utah.edu was used to begin with; it's now added to
mirrors.nix. Note that it doesn't support SSL, but that applies to
several others so I don't see the harm.)

pkgs/build-support/fetchurl/mirrors.nix

@@ -280,6 +280,7 @@ rec {
     http://archive.apache.org/dist/ # fallback for old releases
     ftp://ftp.funet.fi/pub/mirrors/apache.org/
     http://apache.cs.uu.nl/dist/
+    http://apache.cs.utah.edu/
   ];
 
   postgresql = [

pkgs/servers/nosql/cassandra/1.2.nix

@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     inherit sha256;
-    url = "http://apache.cs.utah.edu/cassandra/${version}/apache-${name}-bin.tar.gz";
+    url = "mirror://apache/cassandra/${version}/apache-${name}-bin.tar.gz";
   };
 
   nativeBuildInputs = [ makeWrapper ];

pkgs/servers/nosql/cassandra/2.0.nix

@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     inherit sha256;
-    url = "http://apache.cs.utah.edu/cassandra/${version}/apache-${name}-bin.tar.gz";
+    url = "mirror://apache/cassandra/${version}/apache-${name}-bin.tar.gz";
   };
 
   nativeBuildInputs = [ makeWrapper ];

pkgs/servers/nosql/cassandra/2.1.nix

@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
 
   src = fetchurl {
     inherit sha256;
-    url = "http://apache.cs.utah.edu/cassandra/${version}/apache-${name}-bin.tar.gz";
+    url = "mirror://apache/cassandra/${version}/apache-${name}-bin.tar.gz";
   };
 
   nativeBuildInputs = [ makeWrapper ];