cue2pops: modernize derivation; add missing license

  makeFlags = [ "CC=${stdenv.cc.targetPrefix}cc" ];

  installPhase = ''

    runHook preInstall

    install --directory --mode=755 $out/bin

    install --mode=755 cue2pops $out/bin

    runHook postInstall

  '';

  meta = with lib; {

  meta = {

    description = "Convert CUE to ISO suitable to POPStarter";

    homepage = "https://github.com/makefu/cue2pops-linux";

    maintainers = with maintainers; [ AndersonTorres ];

    platforms = platforms.all;

    # Upstream license is unclear.

    # <https://github.com/ErikAndren/cue2pops-mac/issues/2#issuecomment-673983298>

    license = lib.licenses.unfree;

    maintainers = with lib.maintainers; [ AndersonTorres ];

    platforms = lib.platforms.all;

    mainProgram = "cue2pops";

  };

}