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/arachne-pnr/default.nix

@@ -0,0 +1,42 @@
+{ lib, stdenv, fetchFromGitHub, icestorm }:
+
+stdenv.mkDerivation rec {
+  pname = "arachne-pnr";
+  version = "2019.07.29";
+
+  src = fetchFromGitHub {
+    owner = "yosyshq";
+    repo = "arachne-pnr";
+    rev = "c40fb2289952f4f120cc10a5a4c82a6fb88442dc";
+    sha256 = "0lg9rccr486cvips3jf289af2b4a2j9chc8iqnkhykgi1hw4pszc";
+  };
+
+  enableParallelBuilding = true;
+  makeFlags = [
+    "PREFIX=$(out)"
+    "ICEBOX=${icestorm}/share/icebox"
+  ];
+
+  postPatch = ''
+    substituteInPlace ./Makefile \
+      --replace 'echo UNKNOWN' 'echo ${lib.substring 0 10 src.rev}'
+  '';
+
+  meta = with lib; {
+    description = "Place and route tool for FPGAs";
+    longDescription = ''
+      Arachne-pnr implements the place and route step of
+      the hardware compilation process for FPGAs. It
+      accepts as input a technology-mapped netlist in BLIF
+      format, as output by the Yosys [0] synthesis suite
+      for example. It currently targets the Lattice
+      Semiconductor iCE40 family of FPGAs [1]. Its output
+      is a textual bitstream representation for assembly by
+      the IceStorm [2] icepack command.
+    '';
+    homepage = "https://github.com/cseed/arachne-pnr";
+    license = licenses.mit;
+    maintainers = with maintainers; [ shell thoughtpolice ];
+    platforms = platforms.unix;
+  };
+}