Build free part of Clementine on Hydra

Clementine consists of a large free part (the main application) and a
small part with unfree dependencies (the Spotify blob). Add a top-level
attribute for the free Clementine for users who don't want unfree
software, and so that the bulk of Clementine will be in the binary cache.

pkgs/applications/audio/clementine/default.nix

···
     usbmuxd
   ];
 
-  unwrapped = stdenv.mkDerivation {
-    name = "clementine-unwrapped-${version}";
+  free = stdenv.mkDerivation {
+    name = "clementine-free-${version}";
     inherit patches src buildInputs;
     enableParallelBuilding = true;
     meta = with stdenv.lib; {
···
 
 runCommand "clementine-${version}"
 {
-  inherit blob unwrapped;
+  inherit blob free;
   buildInputs = [ makeWrapper ] ++ gst_plugins; # for the setup-hooks
   dontPatchELF = true;
   dontStrip = true;
···
 }
 ''
   mkdir -p $out/bin
-  makeWrapper "$unwrapped/bin/${exeName}" "$out/bin/${exeName}" \
+  makeWrapper "$free/bin/${exeName}" "$out/bin/${exeName}" \
       ${optionalString withSpotify "--set CLEMENTINE_SPOTIFYBLOB \"$blob/libexec/clementine\""} \
       --prefix GST_PLUGIN_SYSTEM_PATH : "$GST_PLUGIN_SYSTEM_PATH"
 ''

pkgs/top-level/all-packages.nix

···
     gst_plugins = [ gst_plugins_base gst_plugins_good gst_plugins_ugly gst_ffmpeg ];
   };
 
+  clementineFree = clementine.free;
+
   ciopfs = callPackage ../tools/filesystems/ciopfs { };
 
   cmst = callPackage ../tools/networking/cmst { };