WIP: Getting MDX tests working on Windows

Author: polytypic

README.md

@@ -754,6 +754,7 @@ Eio.Io Net Connection_failure Refused Unix_error (Connection refused, "connect",
 If we ran this using another backend, the `Unix_error` part might change.
 To avoid this problem, you can use `Eio.Exn.Backend.show` to hide the backend-specific part of errors:
 
+<!-- $MDX skip -->
 ```ocaml
 # Eio.Exn.Backend.show := false;;
 - : unit = ()

dune

@@ -2,5 +2,4 @@
   (package eio_main)
   (deps (package eio_main) (env_var "EIO_BACKEND"))
   (preludes doc/prelude.ml)
-  (enabled_if (<> %{os_type} "Win32"))
   (files README.md))

eio_windows.opam

@@ -30,4 +30,4 @@ build: [
   ]
 ]
 dev-repo: "git+https://github.com/ocaml-multicore/eio.git"
-#available: [os-family = "windows"]
+#available: [os = "win32"]

lib_eio_windows/dune

@@ -1,12 +1,13 @@
 (library
  (name eio_windows)
  (public_name eio_windows)
- (library_flags :standard -ccopt -lbcrypt -ccopt -lntdll)
+ (library_flags :standard -cclib -lbcrypt -cclib -lntdll)
  (enabled_if (= %{os_type} "Win32"))
  (foreign_stubs
   (language c)
   (include_dirs ../lib_eio/unix/include)
   (names eio_windows_stubs eio_windows_cstruct_stubs))
+ (c_library_flags :standard -lbcrypt -lntdll)
  (libraries eio eio.unix eio.utils fmt))
 
 (rule