LU-8376 ost: enhance end to end bulk cksum error report

LU-8376 ost: enhance end to end bulk cksum error report

Some sites have experienced spurious checksum errors upon bulk
xfers where it is very difficult to determine the source of the
corruption.
With this patch, upon cksum error, full dump of all pages in a
bulk xfer is now possible (enabled via a /proc tunable) on both
Client and OSS sides, to allow easier root cause identification.

sanity.sh/test_77[b,d,f,g]() existing sub-tests results can already
be used to show the effects of this patch, by injecting bulk cksum
error/corruption using OBD_FAIL_[OSC,OST]_CHECKSUM_[SEND,RECEIVE]
fail codes.

sanity.sh/test_77c has been created to specificaly test new dump
on cksum error functionality.

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: I0d200bb6d5c41c55a66ac012fd9cbd8d702d2f3a
Reviewed-on: https://review.whamcloud.com/23960
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>