Function try_first_eligible_deadline 

pub fn try_first_eligible_deadline<M: Memory + Copy>(
    m: M,
    queue: u64,
    cutoff: u64,
) -> (i32, u64, u64)

The deadline of the first eligible task and the shortest queued slice, without removing anything. ENOENT when nothing queued is eligible, EBUSY when the queue is contended.