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>

pkgs/tools/package-management/nixops/optional-virtd.patch

@@ -0,0 +1,24 @@
+diff --git a/nixops/backends/libvirtd.py b/nixops/backends/libvirtd.py
+index bc5f4af7..edd1348b 100644
+--- a/nixops/backends/libvirtd.py
++++ b/nixops/backends/libvirtd.py
+@@ -8,12 +8,18 @@ import shutil
+ import string
+ import subprocess
+ import time
+-import libvirt
+ 
+ from nixops.backends import MachineDefinition, MachineState
+ import nixops.known_hosts
+ import nixops.util
+ 
++try:
++    import libvirt
++except:
++    class libvirt(object):
++        def __getattribute__(self, name):
++            raise ValueError("The libvirt backend has been disabled because of security issues.")
++
+ # to prevent libvirt errors from appearing on screen, see
+ # https://www.redhat.com/archives/libvirt-users/2017-August/msg00011.html
+