Use more resources (up to available limits) if we have multiple QC samples/svcallers.

def parallel_multiplier(items):
    """Use more resources (up to available limits) if we have multiple QC samples/svcallers.
    """
    machines = []
    for data in (xs[0] for xs in items):
        machines.append(max(1, len(get_svcallers(data)), len(dd.get_algorithm_qc(data))))
    return sum(machines)