Arrays in a cycle together settle the same whatever order they're computed in

FuzzRandomEdits found arrays through each other's cells that settled
by the order they were computed in:

- Blocked by a cycle, an array shows #REF!, and another reading it can
  come out smaller for it, clear of the first's inputs, freeing the
  first, which spills and blocks it again. The pair went around until
  the passes ran out, stopping wherever that was. An array a cycle
  blocks twice in a recalculation, freed between, is now held blocked
  for the rest of it, so they end blocked together, as when the cycle
  is found in one go.
- A formula typed reading an array's cells could close a cycle through
  another array that isn't computed again for it. An array still
  blocked by a cycle has every array checked again, once a
  recalculation.
- An array blocked by a cycle counts as spilling over the cells it
  needs; when its formula gives way to a value, the arrays blocked by a
  cycle through those cells are now checked again.

With the cycles found from the formulas as written and the regions in
each other's way, this ships the roadmap's item: fuzzing random edits
for 400 seconds finds nothing, and -randedit.seeds=20000 passes.

commit

60442de7cf9ca95a56eee8935e2ebe0a9acedbed

parent

d2f45924546bd775a1d19a0f77e4f1574e45d3d0

author

Dami <dami.etoile@gmail.com>

kind

fix risk score 1.6 of 3, Jev's estimate