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/doc/manual/development/unit-handling.section.md

@@ -0,0 +1,62 @@
+# Unit handling {#sec-unit-handling}
+
+To figure out what units need to be started/stopped/restarted/reloaded, the
+script first checks the current state of the system, similar to what `systemctl
+list-units` shows. For each of the units, the script goes through the following
+checks:
+
+- Is the unit file still in the new system? If not, **stop** the service unless
+  it sets `X-StopOnRemoval` in the `[Unit]` section to `false`.
+
+- Is it a `.target` unit? If so, **start** it unless it sets
+  `RefuseManualStart` in the `[Unit]` section to `true` or `X-OnlyManualStart`
+  in the `[Unit]` section to `true`. Also **stop** the unit again unless it
+  sets `X-StopOnReconfiguration` to `false`.
+
+- Are the contents of the unit files different? They are compared by parsing
+  them and comparing their contents. If they are different but only
+  `X-Reload-Triggers` in the `[Unit]` section is changed, **reload** the unit.
+  The NixOS module system allows setting these triggers with the option
+  [systemd.services.\<name\>.reloadTriggers](#opt-systemd.services). There are
+  some additional keys in the `[Unit]` section that are ignored as well. If the
+  unit files differ in any way, the following actions are performed:
+
+  - `.path` and `.slice` units are ignored. There is no need to restart them
+    since changes in their values are applied by systemd when systemd is
+    reloaded.
+
+  - `.mount` units are **reload**ed. These mostly come from the `/etc/fstab`
+    parser.
+
+  - `.socket` units are currently ignored. This is to be fixed at a later
+    point.
+
+  - The rest of the units (mostly `.service` units) are then **reload**ed if
+    `X-ReloadIfChanged` in the `[Service]` section is set to `true` (exposed
+    via [systemd.services.\<name\>.reloadIfChanged](#opt-systemd.services)).
+    A little exception is done for units that were deactivated in the meantime,
+    for example because they require a unit that got stopped before. These
+    are **start**ed instead of reloaded.
+
+  - If the reload flag is not set, some more flags decide if the unit is
+    skipped. These flags are `X-RestartIfChanged` in the `[Service]` section
+    (exposed via
+    [systemd.services.\<name\>.restartIfChanged](#opt-systemd.services)),
+    `RefuseManualStop` in the `[Unit]` section, and `X-OnlyManualStart` in the
+    `[Unit]` section.
+
+  - Further behavior depends on the unit having `X-StopIfChanged` in the
+    `[Service]` section set to `true` (exposed via
+    [systemd.services.\<name\>.stopIfChanged](#opt-systemd.services)). This is
+    set to `true` by default and must be explicitly turned off if not wanted.
+    If the flag is enabled, the unit is **stop**ped and then **start**ed. If
+    not, the unit is **restart**ed. The goal of the flag is to make sure that
+    the new unit never runs in the old environment which is still in place
+    before the activation script is run. This behavior is different when the
+    service is socket-activated, as outlined in the following steps.
+
+  - The last thing that is taken into account is whether the unit is a service
+    and socket-activated. If `X-StopIfChanged` is **not** set, the service
+    is **restart**ed with the others. If it is set, both the service and the
+    socket are **stop**ped and the socket is **start**ed, leaving socket
+    activation to start the service when it's needed.