[PR11606] ocaml bindings tests produce binaries in source dir

 - Workaround for ocamlopt producing outputs adjacent to its source inputs, by
   having the tests copy the inputs into temporary directories in the output
   paths before building.

 - Patch by edward-san.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189081 91177308-0d34-0410-b5e6-96231b3b80d8