JoinHashMap probe SIMD short-circuit optimization

[yew1eb]

In join_hash_map.rs probe logic, both SIMD comparisons execute unconditionally:

  let hash_matched = self.map[e].hashes.simd_eq(Simd::splat(hashes[i]));
  let empty = self.map[e].hashes.simd_eq(Simd::splat(0));  // always runs
  if let Some(pos) = (hash_matched | empty).first_set() { ... }