osd: fix session leak in ms_handle_fast_connect

Signed-off-by: Sage Weil <sage@inktank.com>
osd: fix narrow session refcount race

The set_priv() call consumes a ref.  Technically the local 's' is not
actually owned by use by the time we get to the con_front set_priv().

Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #1820 from ceph/wip-osd-refs

osd: fix a session ref leak, and an unlikely race

Reviewed-by: Greg Farnum <greg@inktank.com>