[llvm] [CMake][OCaml] Make OCaml bindings suitable for out-of-tree install (PR #123478)

[via llvm-commits]

alan-j-hu wrote:

@nikic 

See https://github.com/ocaml/opam-source-archives/blob/main/patches/llvm/fix-macos.patch.14.0.6, for example. This patch is necessary to distribute the LLVM OCaml bindings on opam.

In the given CMake snippet, we are working in OCaml land, not C/C++ land. The OCaml compiler generates .so and .a for its outputs, including on Mac.

https://github.com/llvm/llvm-project/pull/123478