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/zfsnap/default.nix

@@ -0,0 +1,42 @@
+{ lib, stdenv, fetchFromGitHub, coreutils, installShellFiles }:
+
+stdenv.mkDerivation rec {
+  version = "2.0.0-beta3";
+  pname = "zfsnap";
+
+  src = fetchFromGitHub {
+    owner = "zfsnap";
+    repo = "zfsnap";
+    rev = "v${version}";
+    sha256 = "0670a5sghvqx32c9gfsird15mg9nqcvwxsrfcjrwc0sj7br9bd2g";
+  };
+
+  nativeBuildInputs = [ installShellFiles ];
+
+  postPatch = ''
+    # Use zfs binaries from PATH, because often the zfs package from nixpkgs is
+    # not the one that should be used
+    substituteInPlace share/zfsnap/core.sh \
+      --replace "ZFS_CMD='/sbin/zfs'" "ZFS_CMD='zfs'" \
+      --replace "ZPOOL_CMD='/sbin/zpool'" "ZPOOL_CMD='zpool'"
+
+    substituteInPlace sbin/zfsnap.sh \
+      --replace "/bin/ls" "${coreutils}/bin/ls"
+  '';
+
+  installPhase = ''
+    mkdir -p $out/bin
+    mv sbin/zfsnap.sh $out/bin/zfsnap
+    mv share $out
+    installManPage man/*/*
+    installShellCompletion completion/*.{bash,zsh}
+  '';
+
+  meta = with lib; {
+    description = "A portable, performant script to make rolling ZFS snapshots easy";
+    homepage = "https://github.com/zfsnap/zfsnap";
+    license = licenses.bsd3;
+    maintainers = with maintainers; [ woffs ];
+    platforms = platforms.linux;
+  };
+}