selftest: run smbtorture3 SMB2-BASIC tests against additional shares

selftest: run smbtorture3 SMB2-BASIC tests against additional shares

This runs the smbtorture3 SMB2-BASIC and smb2.compound_find tests against shares
with "smbd:async dosmode" enabled.

On the vfs_aio_pthread_async_dosmode_force_sync* shares we
force a sync threadpool which ensures we test behaviour on systems that
don't support unshare(CLONE_FS) and also don't support
per-thread-credentials. This simulates the code path of non linux
systems. And makes sure that we don't regress there.

We also test with xattr_tdb and without.

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Ralph Boehme <slow@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Fri Jul 27 16:04:02 CEST 2018 on sn-devel-144