Fix armv6 build failure: "armv6-freebsd-gcc: not found"

Help from:	imp
Sponsored by:	The FreeBSD Foundation
Remove _IP_VHL* macros and related ifdefs.

MFC after:	1 week
Backout r257223,r257224,r257225,r257246,r257710. The changes caused
some regressions in ICMP handling, and right now me and Baptiste
are out of time on analyzing them.

PR:		188253
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
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
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
Make it possible to interrupt login when running in proxy mode.

Sponsored by:	The FreeBSD Foundation
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
Use socket address from accept(2) instead of retrieving it via
getpeername(2).

Sponsored by:	The FreeBSD Foundation
Properly pass the initiator address when running in proxy mode.

Sponsored by:	The FreeBSD Foundation
Constify.

Sponsored by:	The FreeBSD Foundation
Use proper terminology in debug messages.

Sponsored by:	The FreeBSD Foundation
Use consistent punctuation.

Sponsored by:	The FreeBSD Foundation
If we fail to create LUN, try again on next configuration reload.

Sponsored by:	The FreeBSD Foundation
English.

Sponsored by:	The FreeBSD Foundation
Get rid of ISCSIDCLOSE; it wasn't used and is redundant anyway,
because of ISCSIDFAIL.

Sponsored by:	The FreeBSD Foundation
Be more strict with locking for is_waiting_for_iscsid variable.

Sponsored by:	The FreeBSD Foundation
Remove useless debug.

Sponsored by:	The FreeBSD Foundation
When switching variables to flags in r243185 a few cases were missed.
After r263152 this leaves unused variables if route(8) is compiled
without INET support.
Switch the remaining variable accesses to flags and remove now obsolete
variables.

Reviewed by:	glebius
MFC after:	1 week
Set oif only for outgoing packets.

PR:		188543
MFC after:	1 week
Sponsored by:	Yandex LLC