Get MDX tests working on Windows

Author: polytypic

.gitattributes

@@ -0,0 +1,2 @@
+# To work around MDX issues
+README.md text eol=lf

README.md

@@ -752,12 +752,17 @@ 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:
+To avoid this problem, you can use `Eio.Exn.Backend.show`
 
 ```ocaml
 # Eio.Exn.Backend.show := false;;
 - : unit = ()
+```
+
+to hide the backend-specific part of errors:
 
+<!-- $MDX skip -->
+```ocaml
 # Eio_main.run @@ fun env ->
   let net = Eio.Stdenv.net env in
   Switch.run @@ fun sw ->
@@ -842,7 +847,10 @@ let try_mkdir path =
 The checks also apply to following symlinks:
 
 ```ocaml
-# Unix.symlink "dir1" "link-to-dir1"; Unix.symlink "/tmp" "link-to-tmp";;
+# Unix.symlink "dir1" "link-to-dir1";
+  Unix.symlink
+    (if Sys.win32 then Sys.getenv "TEMP" else "/tmp")
+    "link-to-tmp";;
 - : unit = ()
 
 # Eio_main.run @@ fun env ->

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))

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