[OCaml] Synchronize transformations with LLVM-C.

Also, rearrange the functions in a way that allows to quickly
compare C headers and .mli/glue files.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220842 91177308-0d34-0410-b5e6-96231b3b80d8