OCamlbuild.0.15.0

[hhugo]

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.

• Misc: restore CI (unix, macos, windows) (https://github.com/ocaml/ocamlbuild/pull/328, https://github.com/ocaml/ocamlbuild/pull/329, https://github.com/ocaml/ocamlbuild/pull/336, https://github.com/ocaml/ocamlbuild/pull/349 by Hugo Heuzard)
• Remove degraded mode for windows (https://github.com/ocaml/ocamlbuild/pull/333 by Hugo Heuzard)
• Remove light mode (https://github.com/ocaml/ocamlbuild/pull/332 by Hugo Heuzard)
• Make the codebase work on windows native (https://github.com/ocaml/ocamlbuild/pull/329, https://github.com/ocaml/ocamlbuild/pull/333, https://github.com/ocaml/ocamlbuild/pull/334, https://github.com/ocaml/ocamlbuild/pull/338, https://github.com/ocaml/ocamlbuild/pull/339, https://github.com/ocaml/ocamlbuild/pull/342, https://github.com/ocaml/ocamlbuild/pull/343, https://github.com/ocaml/ocamlbuild/pull/344 by Hugo Heuzard)
• No longer treat empty path in PATH env variable as the current working directory (https://github.com/ocaml/ocamlbuild/pull/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. (https://github.com/ocaml/ocamlbuild/pull/30 by Gabriel Scherer, review by whitequark)
• Rename user-rebindable {LINK,COMP}FLAGS into OCB_{LINK,COMP}FLAGS (https://github.com/ocaml/ocamlbuild/pull/303 by Gabriel Scherer)

[hhugo]

Some rev deps testing has been performed on windows. I could not identify any error caused by ocamlbuild

[hhugo]

https://github.com/ocaml/ocamlbuild/pull/348

[hhugo]

I went through the logs and couldn't identify any error causes by ocamlbuild