Test that values of abstract types are not passable. Test that structs with abstract type members are not passable.
Test that values of abstract types are not passable.
Test that structs with abstract type members are not passable.

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