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/backup/rsnapshot.nix

@@ -0,0 +1,75 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.rsnapshot;
+  cfgfile = pkgs.writeText "rsnapshot.conf" ''
+    config_version	1.2
+    cmd_cp	${pkgs.coreutils}/bin/cp
+    cmd_rm	${pkgs.coreutils}/bin/rm
+    cmd_rsync	${pkgs.rsync}/bin/rsync
+    cmd_ssh	${pkgs.openssh}/bin/ssh
+    cmd_logger	${pkgs.inetutils}/bin/logger
+    cmd_du	${pkgs.coreutils}/bin/du
+    cmd_rsnapshot_diff	${pkgs.rsnapshot}/bin/rsnapshot-diff
+    lockfile	/run/rsnapshot.pid
+    link_dest	1
+
+    ${cfg.extraConfig}
+  '';
+in
+{
+  options = {
+    services.rsnapshot = {
+      enable = mkEnableOption "rsnapshot backups";
+      enableManualRsnapshot = mkOption {
+        description = "Whether to enable manual usage of the rsnapshot command with this module.";
+        default = true;
+        type = types.bool;
+      };
+
+      extraConfig = mkOption {
+        default = "";
+        example = ''
+          retains	hourly	24
+          retain	daily	365
+          backup	/home/	localhost/
+        '';
+        type = types.lines;
+        description = ''
+          rsnapshot configuration option in addition to the defaults from
+          rsnapshot and this module.
+
+          Note that tabs are required to separate option arguments, and
+          directory names require trailing slashes.
+
+          The "extra" in the option name might be a little misleading right
+          now, as it is required to get a functional configuration.
+        '';
+      };
+
+      cronIntervals = mkOption {
+        default = {};
+        example = { hourly = "0 * * * *"; daily = "50 21 * * *"; };
+        type = types.attrsOf types.str;
+        description = ''
+          Periodicity at which intervals should be run by cron.
+          Note that the intervals also have to exist in configuration
+          as retain options.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable (mkMerge [
+    {
+      services.cron.systemCronJobs =
+        mapAttrsToList (interval: time: "${time} root ${pkgs.rsnapshot}/bin/rsnapshot -c ${cfgfile} ${interval}") cfg.cronIntervals;
+    }
+    (mkIf cfg.enableManualRsnapshot {
+      environment.systemPackages = [ pkgs.rsnapshot ];
+      environment.etc."rsnapshot.conf".source = cfgfile;
+    })
+  ]);
+}