Function has_live_timer_driver 

pub fn has_live_timer_driver() -> bool

Whether a LIVE host timer driver is currently registered. Lets the embedder report CurrentThread timer availability honestly (e.g. through a capabilities export) instead of guessing: with no live driver a CurrentThread sleep_until would panic, so the capability must read false – including when the only registrants are DEAD (their owning envs torn down), not merely when none ever registered.