Pure OCaml xxhash implementation

fix mlxxhash

+4 -3
+3 -2
src/dune
··· 1 1 (library 2 - (name xxhash) 3 - (public_name mlxxhash)) 2 + (name mlxxhash) 3 + (public_name mlxxhash) 4 + (wrapped false))
+1 -1
test/dune
··· 1 1 (test 2 2 (name test_xxhash) 3 - (libraries xxhash alcotest)) 3 + (libraries mlxxhash alcotest))