Constant bpxe::flow_node::SMALL_INCOMING

pub const SMALL_INCOMING: usize = 8;

Hard-coded size limit for smallvec::SmallVec<[IncomingIndex; _]>

This is a default expectation for maintaining small arrays of incomings that can grow into a heap allocation if it gets over it.

It's chosen as a somewhat arbitrary guess for what can constitute a "normal" flow count.