[RFC] Add num_available_processors

Hi everyone, I'm happy to share my first RFC :) It proposes adding a small function to retrieve the number of available processors; a feature that's commonly found in other programming languages and one that I believe would be a useful addition to PHP. The related PR has already received a bit of early traction, and now that the RFC is complete, I'm looking forward to your feedback! RFC: https://wiki.php.net/RFC/num_available_processors Patch: https://github.com/php/php-src/pull/11137 Best Daniel