libcli/smb: allow unexpected padding in SMB2 IOCTL responses

libcli/smb: allow unexpected padding in SMB2 IOCTL responses

A NetApp Ontap 7.3.7 SMB server add 8 padding bytes to an
offset that's already 8 byte aligned.

RN: Work around special SMB2 IOCTL response behavior of NetApp Ontap 7.3.7
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14607

Pair-Programmed-With: Volker Lendecke <vl@samba.org>

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Fri Jan 15 08:36:34 UTC 2021 on sn-devel-184

(cherry picked from commit 4c6c71e1378401d66bf2ed230544a75f7b04376f)

Autobuild-User(v4-12-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-12-test): Mon Jan 18 08:57:48 UTC 2021 on sn-devel-184