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/tests/overlayfs.nix

@@ -0,0 +1,47 @@
+import ./make-test-python.nix ({ pkgs, ... }: {
+  name = "overlayfs";
+  meta.maintainers = with pkgs.lib.maintainers; [ bachp ];
+
+  nodes.machine = { pkgs, ... }: {
+    virtualisation.emptyDiskImages = [ 512 ];
+    networking.hostId = "deadbeef";
+    environment.systemPackages = with pkgs; [ parted ];
+  };
+
+  testScript = ''
+    machine.succeed("ls /dev")
+
+    machine.succeed("mkdir -p /tmp/mnt")
+
+    # Test ext4 + overlayfs
+    machine.succeed(
+      'mkfs.ext4 -F -L overlay-ext4 /dev/vdb',
+      'mount -t ext4 /dev/vdb /tmp/mnt',
+      'mkdir -p /tmp/mnt/upper /tmp/mnt/lower /tmp/mnt/work /tmp/mnt/merged',
+      # Setup some existing files
+      'echo Replace > /tmp/mnt/lower/replace.txt',
+      'echo Append > /tmp/mnt/lower/append.txt',
+      'echo Overwrite > /tmp/mnt/lower/overwrite.txt',
+      'mount -t overlay overlay -o lowerdir=/tmp/mnt/lower,upperdir=/tmp/mnt/upper,workdir=/tmp/mnt/work /tmp/mnt/merged',
+      # Test new
+      'echo New > /tmp/mnt/merged/new.txt',
+      '[[ "$(cat /tmp/mnt/merged/new.txt)" == New ]]',
+      # Test replace
+      '[[ "$(cat /tmp/mnt/merged/replace.txt)" == Replace ]]',
+      'echo Replaced > /tmp/mnt/merged/replace-tmp.txt',
+      'mv /tmp/mnt/merged/replace-tmp.txt /tmp/mnt/merged/replace.txt',
+      '[[ "$(cat /tmp/mnt/merged/replace.txt)" == Replaced ]]',
+      # Overwrite
+      '[[ "$(cat /tmp/mnt/merged/overwrite.txt)" == Overwrite ]]',
+      'echo Overwritten > /tmp/mnt/merged/overwrite.txt',
+      '[[ "$(cat /tmp/mnt/merged/overwrite.txt)" == Overwritten ]]',
+      # Test append
+      '[[ "$(cat /tmp/mnt/merged/append.txt)" == Append ]]',
+      'echo ed >> /tmp/mnt/merged/append.txt',
+      '[[ "$(cat /tmp/mnt/merged/append.txt)" == "Append\ned" ]]',
+      'umount /tmp/mnt/merged',
+      'umount /tmp/mnt',
+      'udevadm settle',
+    )
+  '';
+})