uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/build-support/docker/tarsum.nix

@@ -0,0 +1,42 @@
+{ stdenv, go, docker, nixosTests }:
+
+stdenv.mkDerivation {
+  name = "tarsum";
+
+  nativeBuildInputs = [ go ];
+  disallowedReferences = [ go ];
+
+  dontUnpack = true;
+
+  CGO_ENABLED = 0;
+  GOFLAGS = "-trimpath";
+  GO111MODULE = "off";
+
+  buildPhase = ''
+    runHook preBuild
+    mkdir tarsum
+    cd tarsum
+    cp ${./tarsum.go} tarsum.go
+    export GOPATH=$(pwd)
+    export GOCACHE="$TMPDIR/go-cache"
+    mkdir -p src/github.com/docker/docker/pkg
+    ln -sT ${docker.moby-src}/pkg/tarsum src/github.com/docker/docker/pkg/tarsum
+    go build
+    runHook postBuild
+  '';
+
+  installPhase = ''
+    runHook preInstall
+    mkdir -p $out/bin
+    cp tarsum $out/bin/
+    runHook postInstall
+  '';
+
+  passthru = {
+    tests = {
+      dockerTools = nixosTests.docker-tools;
+    };
+  };
+
+  meta.platforms = go.meta.platforms;
+}