More for #9374 - Allow smb2.acls torture test to pass against smbd with a POSIX ACLs...

More for #9374 - Allow smb2.acls torture test to pass against smbd with a POSIX ACLs backend.

Change can_delete_directory() to can_delete_directory_fsp(), as
we only ever call this from an open directory file handle.

This allows us to use OpenDir_fsp() instead of OpenDir().
OpenDir() re-checks the ACL on the directory, which may
refuse DIR_LIST permissions. OpenDir_fsp() does not. As
this is a file-server internal check to see if the directory
actually contains any files before setting delete on close,
we can ignore the ACL here (Windows does).