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/zfs-prune-snapshots/default.nix

@@ -0,0 +1,30 @@
+{ lib, stdenv, fetchFromGitHub, go-md2man }:
+
+stdenv.mkDerivation rec {
+  version = "1.3.0";
+  pname = "zfs-prune-snapshots";
+
+  src = fetchFromGitHub {
+    owner = "bahamas10";
+    repo = pname;
+    rev = "v${version}";
+    sha256 = "sha256-udzC4AUXk7h7HpRcz0V+kPECzATAYZtX8z2fvKPCZ/c=";
+  };
+
+  nativeBuildInputs = [ go-md2man ];
+
+  makeTargets = [ "man" ];
+
+  installPhase = ''
+    install -m 755 -D zfs-prune-snapshots $out/bin/zfs-prune-snapshots
+    install -m 644 -D man/zfs-prune-snapshots.1 $out/share/man/man1/zfs-prune-snapshots.1
+  '';
+
+  meta = with lib; {
+    description = "Remove snapshots from one or more zpools that match given criteria";
+    homepage = "https://github.com/bahamas10/zfs-prune-snapshots";
+    license = licenses.mit;
+    maintainers = [ maintainers.ymarkus ];
+    platforms = platforms.all;
+  };
+}