s3sync: delete dead project

According to http://s3sync.net/wiki.html, https://github.com/ms4720/s3sync was
supposed to take over the development but nothing has happened in 4 years.

The project is unfortunately dead and is our only dependency to ruby 1.8.

nixos/doc/manual/release-notes/rl-unstable.xml

···
     </para>
   </listitem>
 
+  <listitem>
+    <para><command>s3sync</command> is removed, as it hasn't been
+    developed by upstream for 4 years and only runs with ruby 1.8.
+    For an actively-developer alternative look at
+    <command>tarsnap</command> and others.
+    </para>
+  </listitem>
+
 </itemizedlist>
 
 </section>

pkgs/tools/networking/s3sync/default.nix

···
-{ stdenv, fetchurl, ruby, makeWrapper }:
-
-stdenv.mkDerivation {
-  name = "s3sync-1.2.6";
-
-  src = fetchurl {
-    url = http://s3.amazonaws.com/ServEdge_pub/s3sync/s3sync.tar.gz; # !!!
-    sha256 = "19467mgym0da0hifhkcbivccdima7gkaw3k8q760ilfbwgwxcn7f";
-  };
-
-  buildInputs = [ makeWrapper ];
-
-  installPhase =
-    ''
-      mkdir -p $out/libexec/s3sync
-      cp *.rb $out/libexec/s3sync
-      makeWrapper "${ruby}/bin/ruby $out/libexec/s3sync/s3cmd.rb" $out/bin/s3cmd
-      makeWrapper "${ruby}/bin/ruby $out/libexec/s3sync/s3sync.rb" $out/bin/s3sync
-
-      mkdir -p $out/share/doc/s3sync
-      cp README* $out/share/doc/s3sync/
-    ''; # */
-
-  meta = {
-    homepage = http://s3sync.net/;
-    description = "Command-line tools to manipulate Amazon S3 buckets";
-    license = stdenv.lib.licenses.free; # some custom as-is in file headers
-  };
-}

pkgs/top-level/all-packages.nix

···
 
   s3cmd = callPackage ../tools/networking/s3cmd { };
 
-  s3sync = callPackage ../tools/networking/s3sync {
-    ruby = ruby_1_8;
-  };
-
   s6Dns = callPackage ../tools/networking/s6-dns { };
 
   s6LinuxUtils = callPackage ../os-specific/linux/s6-linux-utils { };