libceph: ceph_osd_{exists,is_up,is_down}(osd) definitions

Sync up with ceph.git definitions.  Bring in ceph_osd_is_down().

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
1 file changed