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>

nixos/tests/collectd.nix

@@ -0,0 +1,38 @@
+import ./make-test-python.nix ({ pkgs, ... }: {
+  name = "collectd";
+  meta = { };
+
+  nodes.machine =
+    { pkgs, lib, ... }:
+
+    {
+      services.collectd = {
+        enable = true;
+        extraConfig = lib.mkBefore ''
+          Interval 30
+        '';
+        plugins = {
+          rrdtool = ''
+            DataDir "/var/lib/collectd/rrd"
+          '';
+          load = "";
+        };
+      };
+      environment.systemPackages = [ pkgs.rrdtool ];
+    };
+
+  testScript = ''
+    machine.wait_for_unit("collectd.service")
+    hostname = machine.succeed("hostname").strip()
+    file = f"/var/lib/collectd/rrd/{hostname}/load/load.rrd"
+    machine.wait_for_file(file);
+    machine.succeed(f"rrdinfo {file} | logger")
+    # check that this file contains a shortterm metric
+    machine.succeed(f"rrdinfo {file} | grep -F 'ds[shortterm].min = '")
+    # check that interval was set before the plugins
+    machine.succeed(f"rrdinfo {file} | grep -F 'step = 30'")
+    # check that there are frequent updates
+    machine.succeed(f"cp {file} before")
+    machine.wait_until_fails(f"cmp before {file}")
+  '';
+})