[mini-RFC] Disable opcache per script using "declare(cache=0)"

Hi internals, I like to propose an ability to disable opcache caching per script, using declare(cache=0) at start of PHP file. The idea was inspired by preloading usage, when some scripts are actually preloading scenarios and have to be executed, but don't have to be cached. https://github.com/php/php-src/pull/3678 The change is really small in both syntax and implementation, so I wouldn't like to waste time going through the full RFC process. I'm going to commit this into master on Wednesday (November 28), if no objections. Thanks. Dmitry.