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/mail/pfix-srsd.nix

@@ -0,0 +1,56 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.pfix-srsd = {
+      enable = mkOption {
+        default = false;
+        type = types.bool;
+        description = "Whether to run the postfix sender rewriting scheme daemon.";
+      };
+
+      domain = mkOption {
+        description = "The domain for which to enable srs";
+        type = types.str;
+        example = "example.com";
+      };
+
+      secretsFile = mkOption {
+        description = ''
+          The secret data used to encode the SRS address.
+          to generate, use a command like:
+          <literal>for n in $(seq 5); do dd if=/dev/urandom count=1 bs=1024 status=none | sha256sum | sed 's/  -$//' | sed 's/^/          /'; done</literal>
+        '';
+        type = types.path;
+        default = "/var/lib/pfix-srsd/secrets";
+      };
+    };
+  };
+
+  ###### implementation
+
+  config = mkIf config.services.pfix-srsd.enable {
+    environment = {
+      systemPackages = [ pkgs.pfixtools ];
+    };
+
+    systemd.services.pfix-srsd = {
+      description = "Postfix sender rewriting scheme daemon";
+      before = [ "postfix.service" ];
+      #note that we use requires rather than wants because postfix
+      #is unable to process (almost) all mail without srsd
+      requiredBy = [ "postfix.service" ];
+      serviceConfig = {
+        Type = "forking";
+        PIDFile = "/run/pfix-srsd.pid";
+        ExecStart = "${pkgs.pfixtools}/bin/pfix-srsd -p /run/pfix-srsd.pid -I ${config.services.pfix-srsd.domain} ${config.services.pfix-srsd.secretsFile}";
+      };
+    };
+  };
+}