s/icl_pdu_new/icl_pdu_new_empty/g; no functional changes.

Sponsored by:	The FreeBSD Foundation
Remove check for obsolete FreeBSD versions

PR:		194517
Submitted by:	François Tigeot <ftigeot@wolfpond.org>
s/icl_pdu_new_bhs/icl_pdu_new/; no functional changes, just a little
nicer code.

Sponsored by:	The FreeBSD Foundation
Clean up confusing comment.  Move it to the place of code which is
talked about.  Explain where the mentioned trampoline located
(usermode), and the fact that attempt to exit last thread is denied in
kernel (by delegating the work to usermode).

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
agp_intel.c provides support for AGP on Intel chipsets from 440/BX to
875.  This intersects with the agp_i810.c, which supports all Intels
from i810 to Core i5/7.  Both agp_intel.c and agp_i810.c are compiled
into kernel when device agp is specified in config, and agp_i810
attach seems to be selected by chance due to linking order.

Strip support for 810 and later from agp_intel.c.  Since 440-class
chipsets do not support any long-mode capable CPUs, remove agp_intel.c
from amd64 kernel file list.  Note that agp_intel.c is not compiled
into agp.ko on amd64 already.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
If the start bit, PxCMD.ST, is cleared and nothing is in-flight then
PxCI, PxSACT, PxCMD.CCS and PxCMD.CR should be 0.

Reviewed by:	grehan
Restore spares used in "struct tcpcb" and bump "__FreeBSD_version" to
indicate need for kernel module re-compilation.

Sponsored by:	Mellanox Technologies
Clarify TSO segment limit comment and remove two TABs to make lines a
bit shorter.

Sponsored by:	Mellanox Technologies
Fix misplaced read memory barrier in seq.

Impact on capability races was small: it was possible to get a spurious
ENOTCAPABLE (early return), but it was not possible to bypass checks.

Tidy up some comments.
drm: When reading connector mode tunables, list connectors

... and their associated tunables. This gives a way to know the list of
available connectors, no matter the driver.

The problem is that xrandr(1) can list connectors but it uses a
different naming.

MFC after:	1 week
vt(4): Document kern.vt.fb.default_mode and kern.vt.fb.modes.*

Those tunables are used to set a specific mode in vt(4) instead of using
the default mode.

Differential Revision:	https://reviews.freebsd.org/D1098
Reviewed by:	ak@, emaste@, kwm@
MFC after:	1 week
vt(4): Improve the description of kern.vt.fb.modes.$connector

Differential Revision:	https://reviews.freebsd.org/D1098
Submitted by:	emaste@
MFC after:	1 week
Remove unused tests/lib directory

MFC after: 1 week
vt(4): Start new sentences on their own lines

Submitted by:	brueffer@
MFC after:	1 week
Fix XEN kernel build.

Pointy hat to:	jhb
Add support for the multiport feature and fix hot plug races

MFC after:	1 month
Merge remote-tracking branch 'freebsd/master' into hardened/current/master