Verifies that the Zzz-wraps-each-conde-clause + mk-mplus-suspend-on-
paused-left machinery produces fair interleaving and gives finite
prefixes from infinitely-recursive relations:
- listo-aux has no base case under run* but run 4 q ... produces
exactly the four shortest list shapes, in order.
- mk-disj of two infinite generators (ones-gen, twos-gen) with
run 4 q ... must include both 1-prefixed and 2-prefixed answers
(no starvation).
- run* terminates on a goal that has a finite answer set.
3 tests, 246/246 cumulative.