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/elpa2nix.el

@@ -0,0 +1,33 @@
+(require 'package)
+(package-initialize)
+
+(defun elpa2nix-install-package ()
+  (if (not noninteractive)
+      (error "`elpa2nix-install-package' is to be used only with -batch"))
+  (pcase command-line-args-left
+    (`(,archive ,elpa)
+     (progn (setq package-user-dir elpa)
+            (elpa2nix-install-file archive)))))
+
+(defun elpa2nix-install-from-buffer ()
+  "Install a package from the current buffer."
+  (let ((pkg-desc (if (derived-mode-p 'tar-mode)
+                      (package-tar-file-info)
+                    (package-buffer-info))))
+    ;; Install the package itself.
+    (package-unpack pkg-desc)
+    pkg-desc))
+
+(defun elpa2nix-install-file (file)
+  "Install a package from a file.
+The file can either be a tar file or an Emacs Lisp file."
+  (let ((is-tar (string-match "\\.tar\\'" file)))
+    (with-temp-buffer
+      (if is-tar
+          (insert-file-contents-literally file)
+        (insert-file-contents file))
+      (when is-tar (tar-mode))
+      (elpa2nix-install-from-buffer))))
+
+;; Allow installing package tarfiles larger than 10MB
+(setq large-file-warning-threshold nil)