LU-4610 lfsck: fix lfsck, osd-ldiskfs, osd-zfs debug messages

LU-4610 lfsck: fix lfsck, osd-ldiskfs, osd-zfs debug messages

Fix the debug subsystems for osd-ldiskfs, and osd-zfs to use S_OSD
instead of S_MDS for easier debug message filtering, except
osd_scrub.c which is using S_LFSCK instead of S_MDS.

Do not print a D_LFSCK message in osd_otable_it_preload(), since this
is being printed for every inode in the filesystem and fills the logs
if D_LFSCK is enabled.

Fix lfsck_pos_dump() to print the directory hash cookie in hex and
fix up sanity-lfsck test_6a to be able to handle this.

More D_LFSCK debug message for LFSCK check/repair processing. This
is the first step for logging all the LFSCK changes. The next step
will collect these LFSCK debug message and save them in some files
automatically.

Enable D_LFSCK debug by default.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Iff3143f22d3c4750ebe95fbeba8883a325300c1e
Reviewed-on: http://review.whamcloud.com/10579
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>