[m-rev.] diff: Fix build failure on Windows.

[Peter Wang]

library/io.m:
    Include <wchar.h> for the definitions of dev_t and ino_t when
    building for Windows. This became necessary after some recent
    code movement in the io.m module.

diff --git a/library/io.m b/library/io.m
index a4f7501b5..1a5d76b89 100644
--- a/library/io.m
+++ b/library/io.m
@@ -4944,6 +4944,10 @@ have_dotnet :-
     where comparison is compare_file_id.
 
 :- pragma foreign_decl("C", "
+#ifdef MR_WIN32
+  #include <wchar.h>    // for dev_t, ino_t
+#endif
+
 #ifdef MR_HAVE_DEV_T
   typedef   dev_t       ML_dev_t;
 #else
-- 
2.31.0