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/network-filesystems/drbd.nix

@@ -0,0 +1,63 @@
+# Support for DRBD, the Distributed Replicated Block Device.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let cfg = config.services.drbd; in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.drbd.enable = mkOption {
+      default = false;
+      type = types.bool;
+      description = ''
+        Whether to enable support for DRBD, the Distributed Replicated
+        Block Device.
+      '';
+    };
+
+    services.drbd.config = mkOption {
+      default = "";
+      type = types.lines;
+      description = ''
+        Contents of the <filename>drbd.conf</filename> configuration file.
+      '';
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    environment.systemPackages = [ pkgs.drbd ];
+
+    services.udev.packages = [ pkgs.drbd ];
+
+    boot.kernelModules = [ "drbd" ];
+
+    boot.extraModprobeConfig =
+      ''
+        options drbd usermode_helper=/run/current-system/sw/bin/drbdadm
+      '';
+
+    environment.etc."drbd.conf" =
+      { source = pkgs.writeText "drbd.conf" cfg.config; };
+
+    systemd.services.drbd = {
+      after = [ "systemd-udev.settle.service" "network.target" ];
+      wants = [ "systemd-udev.settle.service" ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        ExecStart = "${pkgs.drbd}/sbin/drbdadm up all";
+        ExecStop = "${pkgs.drbd}/sbin/drbdadm down all";
+      };
+    };
+  };
+}