`make test` is broken on OSX

[samoht]

$ make test
ocaml setup.ml -build
/Users/thomas/.opam/system/bin/ocamlfind ocamlopt -shared -linkall lib/profuse.cmxa -o lib/profuse.cmxs
/Users/thomas/.opam/system/bin/ocamlfind ocamlopt -shared -linkall linux/linux.cmxa -o linux/linux.cmxs
ocaml setup.ml -test
ocamlfind ocamlopt -o run_test -package oUnit -package alcotest -package ctypes -package fd-send-recv -package unix-unistd -package unix-errno -package unix-dirent -package unix-sys-stat -package unix-fcntl -package lwt.unix -package lwt.preemptive -g -thread \
        -I ../_build/lib -I ../_build/linux \
        ../_build/lib/opcode.cmx \
        ../_build/lib/fuse.cmx \
        ../_build/lib/view.cmx \
        ../_build/lib/struct_common.cmx \
        ../_build/lib/struct_linux_7_8.cmx \
        ../_build/lib/struct_osx_7_8.cmx \
        ../_build/lib/struct.cmx \
        ../_build/lib/in_common.cmx \
        ../_build/lib/in_linux_7_8.cmx \
        ../_build/lib/in_osx_7_8.cmx \
        ../_build/lib/in.cmx \
        ../_build/lib/out_common.cmx \
        ../_build/lib/out_linux_7_8.cmx \
        ../_build/lib/out_osx_7_8.cmx \
        ../_build/lib/out.cmx \
        ../_build/linux/profuse.cmx \
        ../_build/linux/lofs.cmx \
        -linkpkg test.ml
Undefined symbols for architecture x86_64:
  "_ffi_closure_alloc", referenced from:
      _ctypes_make_function_pointer in libctypes-foreign-base_stubs.a(ffi_call_stubs.o)
  "_ffi_prep_closure_loc", referenced from:
      _ctypes_make_function_pointer in libctypes-foreign-base_stubs.a(ffi_call_stubs.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
File "caml_startup", line 1:
Error: Error during linking

I suspect this is expected because this isrunning linux tests on OSX, but that would be good to fail more graciously.