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/servers/mail/system-sendmail/default.nix

@@ -0,0 +1,40 @@
+{ lib, stdenv, writeText, runtimeShell }:
+
+let script = writeText "script" ''
+  #!${runtimeShell}
+
+  if command -v sendmail > /dev/null 2>&1 && [ "$(command -v sendmail)" != "{{MYPATH}}" ]; then
+    exec sendmail "$@"
+  elif [ -x /run/wrappers/bin/sendmail ]; then
+    exec /run/wrappers/bin/sendmail "$@"
+  elif [ -x /run/current-system/sw/bin/sendmail ]; then
+    exec /run/current-system/sw/bin/sendmail "$@"
+  else
+    echo "Unable to find system sendmail." >&2
+    exit 1
+  fi
+''; in
+stdenv.mkDerivation {
+  pname = "system-sendmail";
+  version = "1.0";
+
+  src = script;
+
+  dontUnpack = true;
+  dontInstall = true;
+
+  buildPhase = ''
+    mkdir -p $out/bin
+    < $src sed "s#{{MYPATH}}#$out/bin/sendmail#" > $out/bin/sendmail
+    chmod +x $out/bin/sendmail
+  '';
+
+  meta = with lib; {
+    description = ''
+      A sendmail wrapper that calls the system sendmail. Do not install as system-wide sendmail!
+    '';
+    platforms = platforms.unix;
+    maintainers = with maintainers; [ ekleog ];
+    mainProgram = "sendmail";
+  };
+}