LU-13115 mdt: handle mdt_pack_sectx_in_reply() errors

LU-13115 mdt: handle mdt_pack_sectx_in_reply() errors

The mdt_pack_secctx_in_reply() contains mo_xattr_get() call
which -ENOENT error should be checked and exit by error path
if needed.

In DNE environment lu_object may lost its LOHA_EXISTS flag
during osp_xattr_get() and that should be handled to don't
proceed with code paths for existent objects.

Test-Parameters: clientselinux mdtcount=4 envdefinitions=ONLY=185a testlist=sanity,sanity,sanity,sanity
Test-Parameters: clientselinux mdtcount=4 testlist=sanity,recovery-small,sanity-sec
Test-Parameters: clientselinux mdtcount=4 testgroup=review-dne-selinux
Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I55ad666f58dd3fae3ed097018aa23ed94818d246
Reviewed-on: https://review.whamcloud.com/37148
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>