* `-t=d` is removed. Use `-t d` instead.
* `--demangle=false` and `--demangle=0` cannot be used. Omit the option.
* `--help-list` is removed. This is a `cl::` specific option.
* llvm-readobj now supports grouped short options as well.
OptTable avoids global option collision if we decide to support multiplexing for binary utilities.
* One-dash long options are still supported.
* `--section-mapping=false` (D57365) is strange but is kept for now.
* Many `cl::opt` variables were unnecessarily external. I added `static` whenever appropriate.