spnego: fix server handling of no optimistic exchange

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14106

Signed-off-by: Isaac Boukris <iboukris@redhat.com>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Sat Oct 12 15:51:42 UTC 2019 on sn-devel-184
31 jobs for iboukris_spnego_v4-11-test in 81 minutes and 21 seconds (queued for 10 seconds)
latest
Status Job ID Name Coverage
  Build
passed #319979549
shared docker
centos7-samba-o3

00:33:07

passed #319979512
shared docker
ctdb

00:44:27

passed #319979541
shared docker
debian9-samba-o3

00:33:16

passed #319979552
shared docker
fedora29-samba-o3

00:33:31

passed #319979555
shared docker
fedora30-samba-o3

00:36:21

passed #319979544
shared docker
opensuse150-samba-o3

00:40:18

passed #319979547
shared docker
opensuse151-samba-o3

00:41:41

passed #319979478
shared docker
others

00:22:12

passed #319979480
shared docker
samba

00:20:41

passed #319979527
samba-ci-private docker
samba-ad-dc-1

00:46:03

passed #319979494
shared docker
samba-ad-dc-2

01:15:47

passed #319979497
shared docker
samba-ad-dc-3

00:54:31

passed #319979500
shared docker
samba-ad-dc-4

01:05:27

passed #319979502
shared docker
samba-ad-dc-5

00:55:47

passed #319979505
shared docker
samba-ad-dc-6

00:40:39

passed #319979521
samba-ci-private docker
samba-ad-dc-backup

00:53:16

passed #319979517
shared docker
samba-ad-dc-ntvfs

00:49:05

passed #319979491
shared docker
samba-ad-member

00:25:47

passed #319979515
shared docker
samba-ctdb

00:57:14

passed #319979524
samba-ci-private docker
samba-fileserver

00:31:13

passed #319979507
shared docker
samba-libs

00:37:59

passed #319979482
shared docker
samba-none-env

01:21:21

passed #319979484
shared docker
samba-nopython

00:29:19

passed #319979485
shared docker
samba-nopython-py2

00:43:53

passed #319979530
samba-ci-private docker
samba-nt4

00:51:44

passed #319979532
samba-ci-private docker
samba-schemaupgrade

00:29:16

passed #319979510
shared docker
samba-static

00:30:26

passed #319979487
shared docker
samba-systemkrb5

00:17:25

passed #319979489
shared docker
samba-xc

00:11:43

passed #319979538
shared docker
ubuntu1604-samba-o3

00:36:01

passed #319979536
shared docker
ubuntu1804-samba-o3

00:34:33