Use the threaded foreign implementation for the tests.
Use the threaded foreign implementation for the tests.

whitequark/ocaml-ctypes,ocamllabs/ocaml-ctypes,ocamllabs/ocaml-ctypes,whitequark/ocaml-ctypes,yallop/ocaml-ctypes,whitequark/ocaml-ctypes,dsheets/ocaml-ctypes,yallop/ocaml-ctypes,dsheets/ocaml-ctypes,dsheets/ocaml-ctypes