LU-1866 fid: cleanup object visibility definition and check

1) The normal fid, IGIF fid, "ROOT" fid, ".lustre" fid are
   used for client-mdt visible objects.

2) Remove redundan osd_igif.{c,h}

3) Hide server-side local root for up layer dir readpage.

4) It is unnecessary to append FID-in-dient for dot name entry.
   Because we can get it from the directory object directly.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: If98de0c15c0cd3a0e93b666a8d48366b0d8a2cb0
Reviewed-on: http://review.whamcloud.com/4901
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>