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/applications/graphics/sane/config.nix

@@ -0,0 +1,53 @@
+{ lib, stdenv }:
+
+{ paths, disabledDefaultBackends ? [] }:
+
+with lib;
+let
+installSanePath = path: ''
+      if [ -e "${path}/lib/sane" ]; then
+        find "${path}/lib/sane" -maxdepth 1 -not -type d | while read backend; do
+          symlink "$backend" "$out/lib/sane/$(basename "$backend")"
+        done
+      fi
+
+      if [ -e "${path}/etc/sane.d" ]; then
+        find "${path}/etc/sane.d" -maxdepth 1 -not -type d | while read conf; do
+          name="$(basename $conf)"
+          if [ "$name" = "dll.conf" ] || [ "$name" = "saned.conf" ] || [ "$name" = "net.conf" ]; then
+            cat "$conf" >> "$out/etc/sane.d/$name"
+          else
+            symlink "$conf" "$out/etc/sane.d/$name"
+          fi
+        done
+      fi
+
+      if [ -e "${path}/etc/sane.d/dll.d" ]; then
+        find "${path}/etc/sane.d/dll.d" -maxdepth 1 -not -type d | while read conf; do
+          symlink "$conf" "$out/etc/sane.d/dll.d/$(basename $conf)"
+        done
+      fi
+    '';
+    disableBackend = backend: ''
+      grep -q '${backend}' $out/etc/sane.d/dll.conf || { echo '${backend} is not a default plugin in $SANE_CONFIG_DIR/dll.conf'; exit 1; }
+      substituteInPlace $out/etc/sane.d/dll.conf --replace '${backend}' '# ${backend} disabled in nixos config'
+    '';
+in
+stdenv.mkDerivation {
+  name = "sane-config";
+  dontUnpack = true;
+
+  installPhase = ''
+    function symlink () {
+      local target=$1 linkname=$2
+      if [ -e "$linkname" ]; then
+        echo "warning: conflict for $linkname. Overriding $(readlink $linkname) with $target."
+      fi
+      ln -sfn "$target" "$linkname"
+    }
+
+    mkdir -p $out/etc/sane.d $out/etc/sane.d/dll.d $out/lib/sane
+  ''
+  + (concatMapStrings installSanePath paths)
+  + (concatMapStrings disableBackend disabledDefaultBackends);
+}