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/libraries/gf2x/default.nix

@@ -0,0 +1,38 @@
+{ stdenv
+, lib
+, fetchgit
+, autoreconfHook
+, optimize ? false # impure hardware optimizations
+}:
+stdenv.mkDerivation rec {
+  pname = "gf2x";
+  version = "1.3.0";
+
+  # upstream has plans to move to gitlab:
+  # https://github.com/NixOS/nixpkgs/pull/45299#issuecomment-564477936
+  src = fetchgit {
+    url = "https://scm.gforge.inria.fr/anonscm/git/gf2x/gf2x.git";
+    rev = "gf2x-${version}";
+    sha256 = "04g5jg0i4vz46b4w2dvbmahwzi3k6b8g515mfw7im1inc78s14id";
+  };
+
+  nativeBuildInputs = [
+    autoreconfHook
+  ];
+
+  # no actual checks present yet (as of 1.2), but can't hurt trying
+  # for an indirect test, run ntl's test suite
+  doCheck = true;
+
+  configureFlags = lib.optionals (!optimize) [
+    "--disable-hardware-specific-code"
+  ];
+
+  meta = with lib; {
+    description = "Routines for fast arithmetic in GF(2)[x]";
+    homepage = "https://gitlab.inria.fr/gf2x/gf2x/";
+    license = licenses.gpl2Plus;
+    maintainers = teams.sage.members;
+    platforms = platforms.unix;
+  };
+}