test.sh: accommodate platforms where root defaults to "ls -A" again.

For now just use "bup ls -a" and "ls -A", which currently match in
behavior.  Of course we'll have to change that to "bup ls -A" once we
fix "bup ls".

Thanks to Thomas Klausner <tk@giga.or.at> for the report.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>