[lld] r300444 - [ELF] - Implemented --compress-debug-sections option.

[Rafael Avila de Espindola via llvm-commits]

> +static bool getCompressDebugSections(opt::InputArgList &Args) {
> +  if (auto *Arg = Args.getLastArg(OPT_compress_debug_sections)) {
> +    StringRef S = Arg->getValue();
> +    if (S == "none")
> +      return false;
> +    if (S == "zlib")
> +      return zlib::isAvailable();

Should it be an error if compression is requested but zlib is not
available?