LU-12605 tgt: check client data size in target_handle_connect()

LU-12605 tgt: check client data size in target_handle_connect()

Check client data size (negtive or excessively large) in case of
memcpy corruption.

Change-Id: Ided26dea0e2bbb79e607c626810834ca947497d4
Reported-by: Alibaba Cloud <yunye.ry@alibaba-inc.com>
Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35711
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>