ceph: Behave better when handling file lock replies.

Fill in the local lock with response data if appropriate,
and don't call posix_lock_file when reading locks.

Signed-off-by: Herb Shiu <herb_shiu@tcloudcomputing.com>
Acked-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>