smbd: Separate aio_pthread indicator from normal EINTR

According to Posix and the Linux open(2) manpage, the open-syscall can
return EINTR. If that happens, core smbd saw this as an indication
that aio_pthread's open function was doing its job. With a real EINTR
without aio_pthread this meant we ended up in a server_exit after 20
seconds, because there was nobody to do the retry.

EINTR is mapped to NT_STATUS_RETRY. Handle this by just retrying after
a second.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=14285
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Thu Feb 20 22:14:25 UTC 2020 on sn-devel-184

(cherry picked from commit aebe427b)
40 jobs for vl/4.12-14285 in 69 minutes and 4 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed centos7-samba-o3 #445842269
docker shared

00:39:51

passed centos8-samba-o3 #445842270
docker shared

00:37:41

passed ctdb #445842232
docker shared

00:41:58

passed debian10-samba-o3 #445842260
docker shared

00:35:43

passed debian9-samba-o3 #445842259
docker shared

00:36:25

passed fedora29-samba-o3 #445842271
docker shared

00:37:18

passed fedora30-samba-o3 #445842273
docker shared

00:36:47

passed fedora31-samba-o3 #445842274
docker shared

00:36:40

passed opensuse150-samba-o3 #445842262
docker shared

00:40:55

passed opensuse151-samba-o3 #445842267
docker shared

00:39:57

passed others #445842205
docker shared

00:14:17

passed samba #445842206
docker shared

00:26:02

passed samba-ad-dc-1 #445842247
docker samba-ci-private

00:47:44

passed samba-ad-dc-1-mitkrb5 #445842250
docker samba-ci-private

00:39:52

passed samba-ad-dc-2 #445842222
docker shared

01:09:01

passed samba-ad-dc-3 #445842225
docker shared

00:46:00

passed samba-ad-dc-4 #445842226
docker shared

00:55:26

passed samba-ad-dc-4-mitkrb5 #445842240
docker shared

00:56:16

passed samba-ad-dc-5 #445842227
docker shared

00:45:42

passed samba-ad-dc-6 #445842228
docker shared

00:37:59

passed samba-ad-dc-backup #445842243
docker samba-ci-private

01:04:52

passed samba-ad-dc-ntvfs #445842237
docker shared

00:52:37

passed samba-admem #445842219
docker shared

00:30:16

passed samba-admem-mit #445842239
docker shared

00:27:48

passed samba-ctdb #445842234
docker shared

00:22:58

passed samba-fileserver #445842245
docker samba-ci-private

00:26:49

passed samba-fuzz #445842231
docker shared

00:32:10

passed samba-ktest-heimdal #445842246
docker samba-ci-private

00:14:13

passed samba-libs #445842229
docker shared

00:40:41

passed samba-mitkrb5 #445842207
docker shared

00:23:51

passed samba-none-env #445842209
docker shared

01:05:15

passed samba-nopython #445842211
docker shared

00:33:57

passed samba-nopython-py2 #445842214
docker shared

00:44:51

passed samba-nt4 #445842248
docker samba-ci-private

00:53:34

passed samba-schemaupgrade #445842249
docker samba-ci-private

00:31:24

passed samba-simpleserver #445842244
docker samba-ci-private

00:19:17

passed samba-static #445842230
docker shared

00:52:35

passed samba-xc #445842216
docker shared

00:08:15

passed ubuntu1604-samba-o3 #445842257
docker shared

00:36:53

passed ubuntu1804-samba-o3 #445842251
docker shared

00:34:28