LU-11367 som: integrate LSOM with lfs find

LU-11367 som: integrate LSOM with lfs find

The patch integrates LSOM functionality with lfs find so that it
is possible to use LSOM functionality directly on the client. The
MDS fills in the mbo_size and mbo_blocks fields from the LSOM
xattr, if the actual size/blocks are not available, and then set
new OBD_MD_FLLSIZE and OBD_MD_FLLBLOCKS flags in the reply so that
the client knows these fields are valid.

The lfs find command adds "--lazy" option to allow the use of LSOM
data from the MDS.

Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I21dfae7c2633dead5d83b438ec340fea4d56c52b
Reviewed-on: https://review.whamcloud.com/33545
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Vitaly Fertman <c17818@cray.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>