s3: smbd: Allow a SHUTDOWN_CLOSE on a file with outstanding aio if there are no clien...

s3: smbd: Allow a SHUTDOWN_CLOSE on a file with outstanding aio if there are no client connections alive.

The process is exiting now so pthreads will never complete to cause
problems.

Remove the knownfail.d/aio_outstanding entry.

Followup-bugfix for:

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14301

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Wed Jun 24 20:14:15 UTC 2020 on sn-devel-184

(cherry picked from commit 205653732064ecf76d3198451240af468806ec14)