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/os-specific/linux/iomelt/default.nix

@@ -0,0 +1,27 @@
+{ stdenv, lib, fetchurl }:
+
+let version = "0.7";
+in stdenv.mkDerivation {
+  pname = "iomelt";
+  inherit version;
+  src = fetchurl {
+    url = "http://iomelt.com/s/iomelt-${version}.tar.gz";
+    sha256 = "1jhrdm5b7f1bcbrdwcc4yzg26790jxl4d2ndqiwd9brl2g5537im";
+  };
+
+  preBuild = ''
+    mkdir -p $out/bin
+    mkdir -p $out/share/man/man1
+
+    substituteInPlace Makefile \
+      --replace /usr $out
+  '';
+
+  meta = with lib; {
+    description = "A simple yet effective way to benchmark disk IO in Linux systems";
+    homepage    = "http://www.iomelt.com";
+    maintainers = with maintainers; [ cstrahan ];
+    license = licenses.artistic2;
+    platforms   = platforms.linux;
+  };
+}