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/filesystems/mkspiffs/default.nix

@@ -0,0 +1,32 @@
+{ lib, stdenv, fetchFromGitHub, git }:
+
+# Changing the variables CPPFLAGS and BUILD_CONFIG_NAME can be done by
+# overriding the same-named attributes. See ./presets.nix for examples.
+
+stdenv.mkDerivation rec {
+  pname = "mkspiffs";
+  version = "0.2.3";
+
+  src = fetchFromGitHub {
+    owner = "igrr";
+    repo = "mkspiffs";
+    rev = version;
+    fetchSubmodules = true;
+    sha256 = "1fgw1jqdlp83gv56mgnxpakky0q6i6f922niis4awvxjind8pbm1";
+  };
+
+  nativeBuildInputs = [ git ];
+  buildFlags = [ "dist" ];
+  installPhase = ''
+    mkdir -p $out/bin
+    cp mkspiffs $out/bin
+  '';
+
+  meta = with lib; {
+    description = "Tool to build and unpack SPIFFS images";
+    license = licenses.mit;
+    homepage = "https://github.com/igrr/mkspiffs";
+    maintainers = with maintainers; [ haslersn ];
+    platforms = platforms.linux;
+  };
+}

pkgs/tools/filesystems/mkspiffs/presets.nix

@@ -0,0 +1,20 @@
+{ lib, mkspiffs }:
+
+# We provide the same presets as the upstream
+
+lib.mapAttrs (
+  name: { CPPFLAGS }:
+  mkspiffs.overrideAttrs (drv: {
+    inherit CPPFLAGS;
+    BUILD_CONFIG_NAME = "-${name}";
+  })
+) {
+  arduino-esp8266.CPPFLAGS = [
+    "-DSPIFFS_USE_MAGIC_LENGTH=0"
+    "-DSPIFFS_ALIGNED_OBJECT_INDEX_TABLES=1"
+  ];
+
+  arduino-esp32.CPPFLAGS = [ "-DSPIFFS_OBJ_META_LEN=4" ];
+
+  esp-idf.CPPFLAGS = [ "-DSPIFFS_OBJ_META_LEN=4" ];
+}