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/emacs/elpa.nix

@@ -0,0 +1,41 @@
+# builder for Emacs packages built for packages.el
+
+{ lib, stdenv, emacs, texinfo, writeText, gcc }:
+
+with lib;
+
+{ pname
+, version
+, src
+, meta ? {}
+, ...
+}@args:
+
+let
+
+  defaultMeta = {
+    homepage = args.src.meta.homepage or "https://elpa.gnu.org/packages/${pname}.html";
+  };
+
+in
+
+import ./generic.nix { inherit lib stdenv emacs texinfo writeText gcc; } ({
+
+  dontUnpack = true;
+
+  installPhase = ''
+    runHook preInstall
+
+    emacs --batch -Q -l ${./elpa2nix.el} \
+        -f elpa2nix-install-package \
+        "$src" "$out/share/emacs/site-lisp/elpa"
+
+    runHook postInstall
+  '';
+
+  meta = defaultMeta // meta;
+}
+
+// removeAttrs args [ "files" "fileSpecs"
+                      "meta"
+                    ])