ocaml: phase 5.1 euler5.ml baseline (smallest multiple of 1..20 = 232792560)

Iteratively takes lcm of running result with i:

  let rec gcd a b = if b = 0 then a else gcd b (a mod b)
  let lcm a b = a * b / gcd a b
  let euler5 n =
    let r = ref 1 in
    for i = 2 to n do
      r := lcm !r i
    done;
    !r

  euler5 20 = 232792560
            = 2^4 * 3^2 * 5 * 7 * 11 * 13 * 17 * 19

Tests gcd_lcm composition (iter 140) on a fresh problem.

109 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -27,6 +27,7 @@
   "exception_user.ml": 26,
   "euler1.ml": 233168,
   "euler2.ml": 4613732,
+  "euler5.ml": 232792560,
   "euler6.ml": 25164150,
   "euler9.ml": 31875000,
   "expr_eval.ml": 16,