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/development/compilers/dotnet/combine-packages.nix

@@ -0,0 +1,20 @@
+packages:
+{ buildEnv, lib }:
+let cli = builtins.head packages;
+in
+assert lib.assertMsg ((builtins.length packages) != 0)
+    ''You must include at least one package, e.g
+      `with dotnetCorePackages; combinePackages [
+          sdk_3_1 aspnetcore_5_0
+       ];`'' ;
+  buildEnv {
+    name = "dotnet-core-combined";
+    paths = packages;
+    pathsToLink = [ "/host" "/packs" "/sdk" "/shared" "/templates" ];
+    ignoreCollisions = true;
+    postBuild = ''
+      cp ${cli}/dotnet $out/dotnet
+      mkdir $out/bin
+      ln -s $out/dotnet $out/bin/
+    '';
+  }