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/tools/build-managers/gprbuild/default.nix

@@ -0,0 +1,65 @@
+{ lib
+, stdenv
+, fetchFromGitHub
+, fetchpatch
+, gprbuild-boot
+, which
+, gnat
+, xmlada
+}:
+
+stdenv.mkDerivation {
+  pname = "gprbuild";
+
+  # See ./boot.nix for an explanation of the gprbuild setupHook,
+  # our custom knowledge base entry and the situation wrt a
+  # (future) gprbuild wrapper.
+  inherit (gprbuild-boot)
+    version
+    src
+    setupHook
+    meta
+    ;
+
+  nativeBuildInputs = [
+    gnat
+    gprbuild-boot
+    which
+  ];
+
+  propagatedBuildInputs = [
+    xmlada
+  ];
+
+  makeFlags = [
+    "ENABLE_SHARED=${if stdenv.hostPlatform.isStatic then "no" else "yes"}"
+    "PROCESSORS=$(NIX_BUILD_CORES)"
+    # confusingly, for gprbuild --target is autoconf --host
+    "TARGET=${stdenv.hostPlatform.config}"
+    "prefix=${placeholder "out"}"
+  ] ++ lib.optionals (!stdenv.hostPlatform.isStatic) [
+    "LIBRARY_TYPE=relocatable"
+  ];
+
+  # Fixes gprbuild being linked statically always
+  patches = lib.optional (!stdenv.hostPlatform.isStatic) (fetchpatch {
+    name = "gprbuild-relocatable-build.patch";
+    url = "https://aur.archlinux.org/cgit/aur.git/plain/relocatable-build.patch?h=gprbuild&id=1d4e8a5cb982e79135a0aaa3ef87654bed1fe4f0";
+    sha256 = "1r3xsp1pk9h666mm8mdravkybmd5gv2f751x2ffb1kxnwq1rwiyn";
+  });
+
+  buildFlags = [ "all" "libgpr.build" ];
+
+  installFlags = [ "all" "libgpr.install" ];
+
+  # link gprconfig_kb db from gprbuild-boot into build dir,
+  # the install process copies its contents to $out
+  preInstall = ''
+    ln -sf ${gprbuild-boot}/share/gprconfig share/gprconfig
+  '';
+
+  # no need for the install script
+  postInstall = ''
+    rm $out/doinstall
+  '';
+}