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/bpftools/default.nix

@@ -0,0 +1,38 @@
+{ lib, stdenv
+, libopcodes, libbfd, libelf, readline
+, linuxPackages_latest, zlib
+, python3, bison, flex
+}:
+
+stdenv.mkDerivation {
+  pname = "bpftools";
+  inherit (linuxPackages_latest.kernel) version src;
+
+  nativeBuildInputs = [ python3 bison flex ];
+  buildInputs = [ libopcodes libbfd libelf zlib readline ];
+
+  preConfigure = ''
+    patchShebangs scripts/bpf_doc.py
+
+    cd tools/bpf
+    substituteInPlace ./bpftool/Makefile \
+      --replace '/usr/local' "$out" \
+      --replace '/usr'       "$out" \
+      --replace '/sbin'      '/bin'
+  '';
+
+  buildFlags = [ "bpftool" "bpf_asm" "bpf_dbg" ];
+
+  installPhase = ''
+    make -C bpftool install
+    install -Dm755 -t $out/bin bpf_asm
+    install -Dm755 -t $out/bin bpf_dbg
+  '';
+
+  meta = with lib; {
+    description = "Debugging/program analysis tools for the eBPF subsystem";
+    license     = [ licenses.gpl2 licenses.bsd2 ];
+    platforms   = platforms.linux;
+    maintainers = with maintainers; [ thoughtpolice ];
+  };
+}