ceph_test_rados_api_io: fix new test

From 0c802e11d9f0ee993994d391d1e00aeb76965d6a.

Signed-off-by: Sage Weil <sage@redhat.com>
Merge remote-tracking branches 'gh/wip-osdmap' and 'gh/wip-librados-fadvise' into wip-sage-testing2