According to its manual page, flags given to mkostemp(3) shouldn't include
O_RDWR, O_CREAT or O_EXCL flags as these are always included. Beyond
those, the only flag that all callers (except a few tests where it
probably doesn't matter) use is O_CLOEXEC, so set that unconditionally.
For now, only add_acls_for_user is tested. When run under root, it
actually sets the acls. When run under non-root, it sets the acls for
the user, which does nothing, but at least calls the functions.
Yu Watanabe