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/installation/installing-virtualbox-guest.section.md

@@ -0,0 +1,59 @@
+# Installing in a VirtualBox guest {#sec-instaling-virtualbox-guest}
+
+Installing NixOS into a VirtualBox guest is convenient for users who
+want to try NixOS without installing it on bare metal. If you want to
+use a pre-made VirtualBox appliance, it is available at [the downloads
+page](https://nixos.org/nixos/download.html). If you want to set up a
+VirtualBox guest manually, follow these instructions:
+
+1.  Add a New Machine in VirtualBox with OS Type \"Linux / Other Linux\"
+
+1.  Base Memory Size: 768 MB or higher.
+
+1.  New Hard Disk of 8 GB or higher.
+
+1.  Mount the CD-ROM with the NixOS ISO (by clicking on CD/DVD-ROM)
+
+1.  Click on Settings / System / Processor and enable PAE/NX
+
+1.  Click on Settings / System / Acceleration and enable \"VT-x/AMD-V\"
+    acceleration
+
+1.  Click on Settings / Display / Screen and select VMSVGA as Graphics
+    Controller
+
+1.  Save the settings, start the virtual machine, and continue
+    installation like normal
+
+There are a few modifications you should make in configuration.nix.
+Enable booting:
+
+```nix
+boot.loader.grub.device = "/dev/sda";
+```
+
+Also remove the fsck that runs at startup. It will always fail to run,
+stopping your boot until you press `*`.
+
+```nix
+boot.initrd.checkJournalingFS = false;
+```
+
+Shared folders can be given a name and a path in the host system in the
+VirtualBox settings (Machine / Settings / Shared Folders, then click on
+the \"Add\" icon). Add the following to the
+`/etc/nixos/configuration.nix` to auto-mount them. If you do not add
+`"nofail"`, the system will not boot properly.
+
+```nix
+{ config, pkgs, ...} :
+{
+  fileSystems."/virtualboxshare" = {
+    fsType = "vboxsf";
+    device = "nameofthesharedfolder";
+    options = [ "rw" "nofail" ];
+  };
+}
+```
+
+The folder will be available directly under the root directory.