goa: fix and clean

pkgs/development/tools/goa/default.nix

@@ -8,32 +8,12 @@ buildGoPackage rec {
   subPackages = [ "goagen" ];
 
   src = fetchFromGitHub {
-    rev = "v${version}";
     owner = "goadesign";
     repo = "goa";
+    rev = "v${version}";
     sha256 = "13401jf907z3qh11h9clb3z0i0fshwkmhx11fq9z6vx01x8x2in1";
   };
 
-  buildInputs = [ makeWrapper ];
-
-  allowGoReference = true;
-
-  outputs = [ "out" ];
-
-  preInstall = ''
-    export bin=$out
-  '';
-
-  postInstall = ''
-    # goagen needs GOPATH to be set
-    wrapProgram $out/bin/goagen \
-      --prefix GOPATH ":" $out/share/go
-
-    # and it needs access to all its dependancies
-    mkdir -p $out/share/go
-    cp -Rv $NIX_BUILD_TOP/go/{pkg,src} $out/share/go/
-  '';
-
   goDeps = ./deps.nix;
 
   meta = with stdenv.lib; {