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/tools/misc/txt2man/default.nix

@@ -0,0 +1,45 @@
+{ lib, stdenv, fetchFromGitHub, coreutils, gawk }:
+
+stdenv.mkDerivation rec {
+  pname = "txt2man";
+  version = "1.7.1";
+
+  src = fetchFromGitHub {
+    owner = "mvertes";
+    repo = "txt2man";
+    rev = "${pname}-${version}";
+    hash = "sha256-Aqi5PNNaaM/tr9A/7vKeafYKYIs/kHbwHzE7+R/9r9s=";
+  };
+
+  makeFlags = [
+    "prefix=${placeholder "out"}"
+  ];
+
+  postPatch = ''
+    for f in bookman src2man txt2man; do
+      substituteInPlace $f \
+        --replace "gawk" "${gawk}/bin/gawk" \
+        --replace "(date" "(${coreutils}/bin/date" \
+        --replace "=cat" "=${coreutils}/bin/cat" \
+        --replace "cat <<" "${coreutils}/bin/cat <<" \
+        --replace "expand" "${coreutils}/bin/expand" \
+        --replace "(uname" "(${coreutils}/bin/uname"
+    done
+  '';
+
+  doCheck = true;
+
+  checkPhase = ''
+    # gawk and coreutils are part of stdenv but will not
+    # necessarily be in PATH at runtime.
+    sh -c 'unset PATH; printf hello | ./txt2man'
+  '';
+
+  meta = with lib; {
+    description = "Convert flat ASCII text to man page format";
+    homepage = "http://mvertes.free.fr/";
+    license = licenses.gpl2;
+    platforms = platforms.unix;
+    maintainers = with maintainers; [ bjornfor ];
+  };
+}