LU-1697 mdt: create OST-objects for open by fid

LU-1697 mdt: create OST-objects for open by fid

Original prcessing for open by fidi gnored the case of OST-objects
to be created because of re-exporting by NFS or O_LOV_DELAY_CREATE
flags, then MDD failed to find useful stripe EA to create releated
OST-objects.

Rename mdt_open_anon_by_fid() to mdt_open_by_fid_lock() to make it
more match the real use cases.

Signed-off-by: Fan Yong <yong.fan@whamcloud.com>
Change-Id: I3c0e4791f6f74fa6b365d41a8e550dba518b39cc
Reviewed-on: http://review.whamcloud.com/3537
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Lai Siyao <laisiyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>