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>

lib/asserts.nix

@@ -0,0 +1,42 @@
+{ lib }:
+
+rec {
+
+  /* Throw if pred is false, else return pred.
+     Intended to be used to augment asserts with helpful error messages.
+
+     Example:
+       assertMsg false "nope"
+       stderr> error: nope
+
+       assert assertMsg ("foo" == "bar") "foo is not bar, silly"; ""
+       stderr> error: foo is not bar, silly
+
+     Type:
+       assertMsg :: Bool -> String -> Bool
+  */
+  # TODO(Profpatsch): add tests that check stderr
+  assertMsg = pred: msg:
+    pred || builtins.throw msg;
+
+  /* Specialized `assertMsg` for checking if val is one of the elements
+     of a list. Useful for checking enums.
+
+     Example:
+       let sslLibrary = "libressl";
+       in assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ]
+       stderr> error: sslLibrary must be one of [
+       stderr>   "openssl"
+       stderr>   "bearssl"
+       stderr> ], but is: "libressl"
+
+     Type:
+       assertOneOf :: String -> ComparableVal -> List ComparableVal -> Bool
+  */
+  assertOneOf = name: val: xs: assertMsg
+    (lib.elem val xs)
+    "${name} must be one of ${
+      lib.generators.toPretty {} xs}, but is: ${
+        lib.generators.toPretty {} val}";
+
+}