Function ziv_round_vec 

pub fn ziv_round_vec<F>(
    p: usize,
    rm: RoundingMode,
    inputs: &[ExactNum],
    compute: F,
) -> ExactNum
where
    F: FnMut(usize, &[ExactNum]) -> ExactNum,

Same Ziv loop as ziv_round, with every input lifted to p_wrk before compute.

MAX_PREC_RETRY still bounds the number of bumps via [bump_prec_retry].