MFC r263740:

Use a less unusual syntax in debug printfs.

Sponsored by:	The FreeBSD Foundation
MFC r264500:

Stop treating LUN 0 as mandatory.  There is no reason to do that.

Sponsored by:	The FreeBSD Foundation
MFC r264524:

Make it possible for the iSCSI target side to operate in both normal
and ICL_KERNEL_PROXY mode, and fix some bit rot so the latter actually
works again.

Sponsored by:	The FreeBSD Foundation
MFC r264525:

Add some stuff to make it easier to figure out for the system administrator
whether the ICL_KERNEL_PROXY stuff got compiled in correctly.

Sponsored by:	The FreeBSD Foundation
MFC r264526:

Properly identify target portal when running in proxy mode.  While here,
remove CTL_ISCSI_CLOSE, it wasn't used or implemented anyway.

Sponsored by:	The FreeBSD Foundation
MFC r264527:

Make it possible to interrupt login when running in proxy mode.

Sponsored by:	The FreeBSD Foundation
MFC r264528:

Rework the way we enable CTL iSCSI port.  Previously conf_apply()
needed it to be already enabled, because listening in proxy mode
requires it; however, it's conf_apply() that opens pidfiles,
so it resulted in port being enabled before pidfile was opened.
This was not so bad, but it was also disabled when pidfile couldn't
be opened due to ctld already running; this means that starting
second ctld instance screwed up the first.

Sponsored by:	The FreeBSD Foundation
MFC r264529:

Use socket address from accept(2) instead of retrieving it via
getpeername(2).

Sponsored by:	The FreeBSD Foundation
MFC r264530:

Properly pass the initiator address when running in proxy mode.

Sponsored by:	The FreeBSD Foundation
MFC r264531:

Constify.

Sponsored by:	The FreeBSD Foundation
MFC r264532:

Use proper terminology in debug messages.

Sponsored by:	The FreeBSD Foundation