[OCaml] Ensure consistent naming.

Specifically:
  * Directories match module names.
  * Test names match module names.
  * The language is called "OCaml", not "Ocaml".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220958 91177308-0d34-0410-b5e6-96231b3b80d8