Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove stray semicolons from the iSCSI code.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Close iSCSI sessions on shutdown

Ensure that all iSCSI sessions are correctly terminated during shutdown.

* Enhances the changes done by r286226 (D3052).
* Add shutdown post sync event to run after filesystem shutdown
(SHUTDOWN_PRI_FIRST) but before CAM shutdown (SHUTDOWN_PRI_DEFAULT).
* Changes iscsi_maintenance_thread to processes terminate in preference to
reconnect.

Reviewed by: trasz
MFC after: 2 weeks
Sponsored by: Multiplay
Differential Revision: https://reviews.freebsd.org/D4429

Extend ICL to add receive offload methods. For software ICL backend
they are no-ops.

MFC after: 1 month
Sponsored by: The FreeBSD Foundation

Make iSCSI initiator keep Initiator Session ID (ISID) across reconnects.

Previously ISID was changed every time, that made impossible correct
persistent reservation, because reconnected session was identified as
completely new one.

Reviewed by: trasz
MFC after: 1 week

We don't need TAILQ for iSCSI PDUs; STAILQ is enough.

Sponsored by: The FreeBSD Foundation

Bring in the new iSCSI target and initiator.

Reviewed by: ken (parts)
Approved by: re (delphij)
Sponsored by: FreeBSD Foundation