Log Message:
ocamlbuild: update to 0.15.0.

0.15.0 (29 Jun 2024):
----------------------
OCamlbuild 0.15.0 comes with first class support for native Windows ports of OCaml
(MinGW64-w64 and MSVC). This support was historically provided by
[opam-repository-mingw](https://fdopen.github.io/opam-repository-mingw/).

- Misc: restore CI (unix, macos, windows)
  (#328, #329, #336, #349 by Hugo Heuzard)
* Remove degraded mode for windows
  (#333 by Hugo Heuzard)
- Remove light mode (#332 by Hugo Heuzard)
- Make the codebase work on windows native
  (#329, #333, #334, #338, #339, #342, #343, #344 by Hugo Heuzard)
* No longer treat empty path in PATH env variable as the current working directory
  (#339 by Hugo Heuzard)
- Emit a warning if several calls are made to
   `Ocamlbuild_plugin.dispatch` -- all calls before the last one are
   ignored, which may not be what users expect.
  (#30 by Gabriel Scherer, review by whitequark)
- Rename user-rebindable {LINK,COMP}FLAGS into OCB_{LINK,COMP}FLAGS
  (#303 by Gabriel Scherer)

0.14.3 (20 Dec 2023):
---------------------

- Add OCaml 5.2 support
  (#325 by Hugo Heuzard)
- Quote Makefile arguments to allow spaces in paths, especially on Windows.
  Documented in #321 (#324 by Jonah Beckford)