LU-4719 mdt: Don't try to print non-existent objects

LU-4719 mdt: Don't try to print non-existent objects

mdt_dump_lmm() needs to make sure it's not trying to print
objects for a default striping from a directory, since there
are not objects in this case.

Return early if the D_INFO debug mask is disenabled, so it
doesn't iterate through the LOV/LMV layout at all.  That is
just a waste of effort.

Change-Id: I2fffdaefad2a6b05247676441451fffdca620dcd
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/9520
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Reviewed-by: Matt Ezell <ezellma@ornl.gov>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>