ocaml: phase 5.1 triangle_div.ml baseline (first triangle with >10 divisors = 120)

PE12 with target = 10:

  let count_divisors n =
    let c = ref 0 in
    let i = ref 1 in
    while !i * !i <= n do
      if n mod !i = 0 then begin
        c := !c + 1;
        if !i * !i <> n then c := !c + 1
      end;
      i := !i + 1
    done;
    !c

  let first_triangle_with_divs target =
    walk triangles T(n) = T(n-1) + n until count_divisors T > target

T(15) = 120 has 16 divisors — first to exceed 10. Real PE12 uses
target 500 (answer 76576500); 10 stays well under budget.

126 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -122,6 +122,7 @@
   "sum_squares.ml": 385,
   "tree_depth.ml": 4,
   "triangle.ml": 11,
+  "triangle_div.ml": 120,
   "twosum.ml": 5,
   "unique_set.ml": 9,
   "validate.ml": 417,