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/tools/backup/easysnap/default.nix

@@ -0,0 +1,31 @@
+{lib, stdenv, fetchFromGitHub, zfs }:
+
+stdenv.mkDerivation {
+  pname = "easysnap";
+  version = "unstable-2020-04-04";
+
+  src = fetchFromGitHub {
+    owner = "sjau";
+    repo = "easysnap";
+    rev = "26f89c0c3cda01e2595ee19ae5fb8518da25b4ef";
+    sha256 = "1k49k1m7y8s099wyiiz8411i77j1156ncirynmjfyvdhmhcyp5rw";
+  };
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp -n easysnap* $out/bin/
+
+    for i in $out/bin/*; do
+      substituteInPlace $i \
+        --replace zfs ${zfs}/bin/zfs
+    done
+  '';
+
+  meta = with lib; {
+    homepage    = "https://github.com/sjau/easysnap";
+    description = "Customizable ZFS Snapshotting tool with zfs send/recv pulling";
+    license     = licenses.gpl3;
+    maintainers = with maintainers; [ sjau ];
+  };
+
+}