ocaml: phase 5.1 safe_div.ml baseline + Result.equal/compare/iter_error (+3 tests, 592 total)

safe_div.ml: integer division returning Result. Sum-safe folds pairs,
skipping the Error branches.

  [(10,2); (20,4); (30,0); (50,5)]   ->  5 + 5 + 0 + 10 = 20

Result module additions (mirroring real OCaml's signatures):

  equal eq_ok eq_err a b
  compare cmp_ok cmp_err a b      Ok < Error (i.e. Ok x compared to
                                  Error e returns -1)
  iter_error f r

  Result.equal (=) (=) (Ok 1) (Ok 1)              = true
  Result.compare compare compare (Ok 5) (Ok 3)    = 1
  Result.compare compare compare (Ok 1) (Error _) = -1

30 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -26,6 +26,7 @@
   "queens.ml": 2,
   "quicksort.ml": 44,
   "roman.ml": 44,
+  "safe_div.ml": 20,
   "sieve.ml": 15,
   "sum_squares.ml": 385,
   "unique_set.ml": 9,