Log Message:
ocamlbuild: update to 0.16.0.

0.16.0 (13 Feb 2025):
---------------------

OCamlbuild 0.16.0 improves ocamlbuild's behavior
when cross-compiling for Windows.

- Set default values of `Options.ext_*` and `Options.exe` from the output of
  `Options.ocamlc "-config"` (Useful when `Options.ocamlc` is a cross \ 
compiler)
  (#353 by Pierre Boutillier, reviewed by Kate Deplaix and Hugo Heuzard,
   requested by whitequark in #181)
- Misc: continue improving the CI
  (#355 by Hugo Heuzard)