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/trivial-builders/test/references.nix

@@ -0,0 +1,54 @@
+{ lib, testers, pkgs, writeText, hello, figlet, stdenvNoCC }:
+
+# -------------------------------------------------------------------------- #
+#
+#                         trivial-builders test
+#
+# -------------------------------------------------------------------------- #
+#
+#  This file can be run independently (quick):
+#
+#      $ pkgs/build-support/trivial-builders/references-test.sh
+#
+#  or in the build sandbox with a ~20s VM overhead
+#
+#      $ nix-build -A tests.trivial-builders.references
+#
+# -------------------------------------------------------------------------- #
+
+let
+  invokeSamples = file:
+    lib.concatStringsSep " " (
+      lib.attrValues (import file { inherit pkgs; })
+    );
+in
+testers.nixosTest {
+  name = "nixpkgs-trivial-builders";
+  nodes.machine = { ... }: {
+    virtualisation.writableStore = true;
+
+    # Test runs without network, so we don't substitute and prepare our deps
+    nix.settings.substituters = lib.mkForce [];
+    environment.etc."pre-built-paths".source = writeText "pre-built-paths" (
+      builtins.toJSON [hello figlet stdenvNoCC]
+    );
+    environment.variables = {
+      SAMPLE = invokeSamples ./sample.nix;
+      REFERENCES = invokeSamples ./invoke-writeReferencesToFile.nix;
+      DIRECT_REFS = invokeSamples ./invoke-writeDirectReferencesToFile.nix;
+    };
+  };
+  testScript =
+    ''
+      machine.succeed("""
+        ${./references-test.sh} 2>/dev/console
+      """)
+    '';
+  meta = {
+    license = lib.licenses.mit; # nixpkgs license
+    maintainers = with lib.maintainers; [
+      roberth
+    ];
+    description = "Run the Nixpkgs trivial builders tests";
+  };
+}