directory: restore check against standard input

We could handle directories as descriptors, but we currently don't. In
the mean time, we had better show an error than generate corrupt
playlist entries.

modules/access/file.c

@@ -192,6 +192,8 @@ int Open( vlc_object_t *p_this )
      * how to parse the data. The directory plugin will do it. */
     if (S_ISDIR (st.st_mode))
     {
+        if (!strcasecmp (p_access->psz_access, "fd"))
+            goto error; /* fd:// not supported for directories yet */
 #ifdef HAVE_FDOPENDIR
         DIR *handle = fdopendir (fd);
         if (handle == NULL)