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/modules/services/misc/cpuminer-cryptonight.nix

@@ -0,0 +1,66 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.cpuminer-cryptonight;
+
+  json = builtins.toJSON (
+    cfg // {
+       enable = null;
+       threads =
+         if cfg.threads == 0 then null else toString cfg.threads;
+    }
+  );
+
+  confFile = builtins.toFile "cpuminer.json" json;
+in
+{
+
+  options = {
+
+    services.cpuminer-cryptonight = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable the cpuminer cryptonight miner.
+        '';
+      };
+      url = mkOption {
+        type = types.str;
+        description = "URL of mining server";
+      };
+      user = mkOption {
+        type = types.str;
+        description = "Username for mining server";
+      };
+      pass = mkOption {
+        type = types.str;
+        default = "x";
+        description = "Password for mining server";
+      };
+      threads = mkOption {
+        type = types.int;
+        default = 0;
+        description = "Number of miner threads, defaults to available processors";
+      };
+    };
+
+  };
+
+  config = mkIf config.services.cpuminer-cryptonight.enable {
+
+    systemd.services.cpuminer-cryptonight = {
+      description = "Cryptonight cpuminer";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
+      serviceConfig = {
+        ExecStart = "${pkgs.cpuminer-multi}/bin/minerd --syslog --config=${confFile}";
+        User = "nobody";
+      };
+    };
+
+  };
+
+}