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/build-support/release/rpm-build.nix

@@ -0,0 +1,54 @@
+# This function builds an RPM from a source tarball that contains a
+# RPM spec file (i.e., one that can be built using `rpmbuild -ta').
+
+{ name ? "rpm-build"
+, diskImage
+, src, vmTools
+, ... } @ args:
+
+vmTools.buildRPM (
+
+  removeAttrs args ["vmTools"] //
+
+  {
+    name = name + "-" + diskImage.name + (if src ? version then "-" + src.version else "");
+
+    preBuild = ''
+      . ${./functions.sh}
+      propagateImageName
+      src=$(findTarball $src)
+    '';
+
+    postInstall = ''
+      declare -a rpms rpmNames
+      for i in $out/rpms/*/*.rpm; do
+        if echo $i | grep -vq "\.src\.rpm$"; then
+          echo "file rpm $i" >> $out/nix-support/hydra-build-products
+          rpms+=($i)
+          rpmNames+=("$(rpm -qp "$i")")
+        fi
+      done
+
+      echo "installing ''${rpms[*]}..."
+      rpm -Up ''${rpms[*]} --excludepath /nix/store
+
+      eval "$postRPMInstall"
+
+      echo "uninstalling ''${rpmNames[*]}..."
+      rpm -e ''${rpmNames[*]} --nodeps
+
+      for i in $out/rpms/*/*.src.rpm; do
+        echo "file srpm $i" >> $out/nix-support/hydra-build-products
+      done
+
+      for rpmdir in $extraRPMs ; do
+        echo "file rpm-extra $(ls $rpmdir/rpms/*/*.rpm | grep -v 'src\.rpm' | sort | head -1)" >> $out/nix-support/hydra-build-products
+      done
+    '';
+
+    meta = (if args ? meta then args.meta else {}) // {
+      description = "RPM package for ${diskImage.fullName}";
+    };
+  }
+
+)