support/testing: add missing systemd-overlay-fstab
Commit 083e65a67c84f83a3403c92c51d89f8c94907c55 introduced tests for the
various read-only root options under systemd, but while applying the
fs-overlay that is used in one of the tests wasn't included. Include it
now.
Fixes: 083e65a67c84f83a3403c92c51d89f8c94907c55
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
Arnout Vandecappelle