LU-2921 iokit: plot-obdfilter fixes

plot-obdfilter was mixing up objects and threads in its output.

Signed-off-by: Robert Read <robert.read@intel.com>
Change-Id: If6aa66943b88ea0d35b5a8ab4b61b8f80df67fd5
Reviewed-on: http://review.whamcloud.com/5618
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>