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/ocaml-modules/mirage-xen/default.nix

@@ -0,0 +1,78 @@
+{ lib
+, buildDunePackage
+, fetchurl
+, pkg-config
+, cstruct
+, lwt
+, shared-memory-ring-lwt
+, xenstore
+, lwt-dllist
+, mirage-profile
+, mirage-runtime
+, logs
+, fmt
+, ocaml-freestanding
+, bheap
+, duration
+, io-page
+}:
+
+buildDunePackage rec {
+  pname = "mirage-xen";
+  version = "6.0.0";
+
+  useDune2 = true;
+
+  src = fetchurl {
+    url = "https://github.com/mirage/mirage-xen/releases/download/v${version}/mirage-xen-v${version}.tbz";
+    sha256 = "f991e972059b27993c287ad010d9281fee061efaa1dd475d0955179f93710fbd";
+  };
+
+  patches = [
+    ./makefile-no-opam.patch
+    ./pkg-config.patch
+  ];
+
+  # can't handle OCAMLFIND_DESTDIR with substituteAll
+  postPatch = ''
+    substituteInPlace lib/bindings/mirage-xen.pc \
+      --replace "@out@" "$out" \
+      --replace "@OCAMLFIND_DESTDIR@" "$OCAMLFIND_DESTDIR"
+  '';
+
+  minimumOCamlVersion = "4.08";
+
+  nativeBuildInputs = [
+    pkg-config
+  ];
+
+  propagatedBuildInputs = [
+    cstruct
+    lwt
+    shared-memory-ring-lwt
+    xenstore
+    lwt-dllist
+    mirage-profile
+    mirage-runtime
+    io-page
+    logs
+    fmt
+    bheap
+    duration
+    (ocaml-freestanding.override { target = "xen"; })
+  ];
+
+  # Move pkg-config files into their well-known location.
+  # This saves us an extra setup hook and causes no issues
+  # since we patch all relative paths out of the .pc file.
+  postInstall = ''
+    mv $OCAMLFIND_DESTDIR/pkgconfig $out/lib/pkgconfig
+  '';
+
+  meta = with lib; {
+    description = "Xen core platform libraries for MirageOS";
+    license = licenses.isc;
+    maintainers = [ maintainers.sternenseemann ];
+    homepage = "https://github.com/mirage/mirage-xen";
+  };
+}