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/audio/mpdcron/gemset.nix

@@ -0,0 +1,23 @@
+{
+  mini_portile2 = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "15zplpfw3knqifj9bpf604rb3wc1vhq6363pd6lvhayng8wql5vy";
+      type = "gem";
+    };
+    version = "2.4.0";
+  };
+  nokogiri = {
+    dependencies = ["mini_portile2"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "02bjydih0j515szfv9mls195cvpyidh6ixm7dwbl3s2sbaxxk5s4";
+      type = "gem";
+    };
+    version = "1.10.3";
+  };
+}