ocaml: phase 5.1 kmp.ml baseline (5 occurrences of "abab" in haystack)

Knuth-Morris-Pratt linear-time string search:
  - kmp_table builds failure function in O(|pattern|)
  - kmp_search scans text once in O(|text|), counting matches
  - After a hit, k := t.(n-1) so overlapping matches still count

  kmp_search "abababcabababcababcc" "abab" = 5

Hits at positions 0, 2, 7, 9, 14 (overlapping at 0/2 and 7/9).

Tests: nested while-inside-for, char inequality (.<>), pat.[i]
string indexing, Array.make 0, combined string + array indexing.

140 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -79,6 +79,7 @@
   "josephus.ml": 11,
   "json_pretty.ml": 24,
   "kadane.ml": 6,
+  "kmp.ml": 5,
   "lambda_calc.ml": 7,
   "majority_vote.ml": 4,
   "levenshtein.ml": 11,