LU-1303 lod: propagate real object size on a new striping

LU-1303 lod: propagate real object size on a new striping

it's possible to truncate file with no striping, when create
striping. in such a case lod's object create propagate actual
size down to the stack.

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Change-Id: Iaf4a91516892db23f11052bd1a656ee2108a7113
Reviewed-on: http://review.whamcloud.com/4059
Reviewed-by: wangdi <di.wang@whamcloud.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Mike Pershin <tappro@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>