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/system/kerberos/default.nix

@@ -0,0 +1,75 @@
+{config, lib, ...}:
+
+let
+  inherit (lib) mkOption mkIf types length attrNames;
+  cfg = config.services.kerberos_server;
+  kerberos = config.krb5.kerberos;
+
+  aclEntry = {
+    options = {
+      principal = mkOption {
+        type = types.str;
+        description = "Which principal the rule applies to";
+      };
+      access = mkOption {
+        type = types.either
+          (types.listOf (types.enum ["add" "cpw" "delete" "get" "list" "modify"]))
+          (types.enum ["all"]);
+        default = "all";
+        description = "The changes the principal is allowed to make.";
+      };
+      target = mkOption {
+        type = types.str;
+        default = "*";
+        description = "The principals that 'access' applies to.";
+      };
+    };
+  };
+
+  realm = {
+    options = {
+      acl = mkOption {
+        type = types.listOf (types.submodule aclEntry);
+        default = [
+          { principal = "*/admin"; access = "all"; }
+          { principal = "admin"; access = "all"; }
+        ];
+        description = ''
+          The privileges granted to a user.
+        '';
+      };
+    };
+  };
+in
+
+{
+  imports = [
+    ./mit.nix
+    ./heimdal.nix
+  ];
+
+  ###### interface
+  options = {
+    services.kerberos_server = {
+      enable = lib.mkEnableOption "the kerberos authentification server";
+
+      realms = mkOption {
+        type = types.attrsOf (types.submodule realm);
+        description = ''
+          The realm(s) to serve keys for.
+        '';
+      };
+    };
+  };
+
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ kerberos ];
+    assertions = [{
+      assertion = length (attrNames cfg.realms) <= 1;
+      message = "Only one realm per server is currently supported.";
+    }];
+  };
+}