ocaml: phase 4 bitwise ops land/lor/lxor/lsl/lsr/asr + bits.ml baseline (+5 tests, 607 total)

The binop precedence table already had land/lor/lxor/lsl/lsr/asr
(iter 0 setup) but eval-op fell through to 'unknown operator' for
all of them. SX doesn't expose host bitwise primitives, so each is
implemented in eval.sx via arithmetic on the host:

  land/lor/lxor:  mask & shift loop, accumulating 1<<k digits
  lsl k:          repeated * 2 k times
  lsr k:          repeated floor (/ 2) k times
  asr:            aliased to lsr (no sign extension at our bit width)

bits.ml baseline: popcount via 'while m > 0 do if m land 1 = 1 then
... ; m := m lsr 1 done'. Sum of popcount(1023, 5, 1024, 0xff) = 10
+ 2 + 1 + 8 = 21.

  5 land 3 = 1
  5 lor 3 = 7
  5 lxor 3 = 6
  1 lsl 8 = 256
  256 lsr 4 = 16

41 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -2,6 +2,7 @@
   "ackermann.ml": 125,
   "anagrams.ml": 3,
   "bag.ml": 3,
+  "bits.ml": 21,
   "balance.ml": 3,
   "bfs.ml": 6,
   "btree.ml": 39,