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/melpa2nix.el

@@ -0,0 +1,32 @@
+(require 'package)
+(package-initialize)
+
+(require 'package-recipe)
+(require 'package-build)
+
+(setq package-build-working-dir (expand-file-name "working/"))
+(setq package-build-archive-dir (expand-file-name "packages/"))
+(setq package-build-recipes-dir (expand-file-name "recipes/"))
+
+;; Allow installing package tarfiles larger than 10MB
+(setq large-file-warning-threshold nil)
+
+(defun melpa2nix-build-package-1 (rcp version commit)
+  (let ((source-dir (package-recipe--working-tree rcp)))
+    (unwind-protect
+        (let ((files (package-build-expand-files-spec rcp t)))
+          (cond
+           ((= (length files) 1)
+            (package-build--build-single-file-package
+             rcp version commit files source-dir))
+           ((> (length files) 1)
+            (package-build--build-multi-file-package
+             rcp version commit files source-dir))
+           (t (error "Unable to find files matching recipe patterns")))))))
+
+(defun melpa2nix-build-package ()
+  (if (not noninteractive)
+      (error "`melpa2nix-build-package' is to be used only with -batch"))
+  (pcase command-line-args-left
+    (`(,package ,version ,commit)
+     (melpa2nix-build-package-1 (package-recipe-lookup package) version commit))))