[OCaml] [cmake] Add CMake buildsystem for OCaml.

Closes PR15325.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223071 91177308-0d34-0410-b5e6-96231b3b80d8
[OCaml] Move Llvm.clone_module to its own Llvm_transform_utils module.

This way most code won't link this (substantially large) library,
if compiled statically with LLVM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223072 91177308-0d34-0410-b5e6-96231b3b80d8