vt(4): Fix keyboard allocation when kbdmux(4) isn't used

The problem was that only the kbdmux keyboard index was saved in
vd->vd_keyboard. This index is -1 when kbdmux isn't used. In this
case, the keyboard was correctly allocated, but the returned index was
discarded.

PR:		194718
MFC of:		r273973
drm: Lower priority of three messages related to invalid EDID

Like in r259717, the prority goes from "error" to "debug" to avoid
spamming logs when the connectors are polled.

PR:		194770
Submitted by:	Larry Rosenman <ler@lerctr.org>
MFC of:		r273962, r274587
drm: Take vt(4) default mode from loader tunables

By default, vt(4) gets the "preferred mode" from DRM, when using a DRM
video driver as its backend. The preferred mode is usually the native
screen resolution.

Now, if this mode isn't appropriate, a user can use loader tunables to
select a mode. The tunables are read in the following order:
    1. kern.vt.fb.modes.$connector_name
    2. kern.vt.fb.default_mode

For example, to set a 1024x768 mode, no matter the connector:
    kern.vt.fb.default_mode="1024x768"

To set a 800x600 mode only on the laptop builtin screen:
    kern.vt.fb.modes.LVDS-1="800x600"

Beside r274031, this MFC includes:

r274049:
  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.

r274050:
  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@

r274051:
  vt(4): Improve the description of kern.vt.fb.modes.$connector

  Differential Revision:	https://reviews.freebsd.org/D1098
  Submitted by:	emaste@

r274053:
  vt(4): Start new sentences on their own lines

  Submitted by:	brueffer@

MFC of:		r274031, r274049, r274050, r274051, r274053
MFC r273459:

Untangle iSCSI authentication code by splitting off the CHAP
implementation.

Sponsored by:	The FreeBSD Foundation
vt(4): Support syscons' SC_HISTORY_SIZE to configure history size

Therefore, to set histry size to 2000 lines, add the following line to
your kernel configuration file:
    options SC_HISTORY_SIZE=2000

The default history remains at 500 lines.

MFC of:		r274117
MFC r271320:

Use keys_add_int() where appropriate.  No functional changes.

Sponsored by:	The FreeBSD Foundation
MFC r273464:

Whitespace fixes.

Sponsored by:	The FreeBSD Foundation
MFC r273465:

Fix ctld(8) to not show the "auth-group <name> not assigned to any target"
warning for auth-groups assigned to a portal-group.

Sponsored by:	The FreeBSD Foundation
MFC r273466:

Remove spurious empty line.

Sponsored by:	The FreeBSD Foundation
MFC r273468:

Remove misleading statement.  Bump date.

Sponsored by:	The FreeBSD Foundation
MFC r273543:

Clean up (refactor) discovery a little; no functional changes.

Sponsored by:	The FreeBSD Foundation
MFC:
	------------------------------------------------------------------------
	r274792 | n_hibma | 2014-11-21 15:53:42 +0100 (Fri, 21 Nov 2014) | 5
	lines

	Simply remove the tmp dir before creating the symlink. We are doing
	chroots all over the place, so there is bound to be a stale file lying
	around in there (in my case samba lock files from creating accounts). If
	we don't do that, the symlink later will fail.

	------------------------------------------------------------------------