Arrange for the following files to be compiled when the configuration
conditions are met rather than having to resort to #if's in the code.
> dev/syscons/scvgarndr.c               optional        sc vga
> dev/syscons/scvesactl.c               optional        sc vga vesa
> i386/isa/vesa.c                       optional        vga vesa
Use config's conditional compilation rather than using #ifdefs that make
modular compilation harder.  I'm doing this because people seem to like
cut/pasting examples of bad practices in existing code.
This patch fixes a locking bug that can result in deadlock if
the codepath is followed.

From the PR:

  vclean calls vrele leading to deadlock (if usecount > 0)

  vclean() calls vrele() if v_usecount of the node was higher than one.
  But before calling it, it sets the VXLOCK flag, which will make
  vn_lock called from vrele dead-lock.

PR:		kern/15117
Submitted by:	Assar Westerlund <assar@stacken.kth.se>
Reviewed by:	rwatson
Obtained from:	NetBSD
Increase the default msgbuf size from 8k to 32k.  Boot -v easily
overflows the default buffer making it too hard to get a dmesg from
a verbose boot.  It's still changeable via an option, so if picobsd
needs to set it to something else they still can.

Reviewed by:	phk, alfred
Put a FYI in the compatability shims so that people are aware that they
are using an old unconverted driver.  Most (if not all) of the drivers
for common hardware are newbus these days.  However, we don't want
to encourage people to take the easy way out and write new drivers
using the shims.  This is just passive "encouragement".

Reviewed by:	phk
Dont confuse our users with this, the ata driver uses burncd.
Unbreak LINT.

Pointed out by:   Peter Wemm
Don't build the wdc atapi attachments unless wdc is also present.
Remove #if NFOO > 0 (it's not required in most cases) and also where it
isn't used as a result, remove #include "foo.h".  Many of these drivers
still use NFOO for softc struct sizing etc however.
Fix this so LINT compiles.  There is no way this could have worked if
tested with LINT.  I've put back netatm/kern_include.h and maked it
with a fixme!, otherwise NETISR_ATM isn't defined as ATM_KERNEL isn't
defined.  Defining that exposes a whole bunch of other dependencies.. :-(
Remove a bunch of unused (NO-OP) #if NFOO > 0 type includes and some
#include "foo.h" headers.
Remove a warning from LINT
Remove sys/tablet.h and kern/tty_tb.c (the old RS232 CAD-style tablet
support code).  It hasn't worked since at least October 1995, and probably
has never worked in the FreeBSD 2.0+ tree.  Obviously it's not a priority
to many folks.

Reviewed by:	phk, sos
Remove kern/tty_tb.c.
Remove (commented out and marked as broken) pseudo-device tb.  This was
added in rev 1.205 (october 1995).
Clean up some compilation warnings and errors.
Put tslb_device structure in this file. Put a pointer to to primary
CPU's structure.
Update copyright and pull some newer definitions from NetBSD version.
Don't report the tablet line discipline, it "doesn't happen (TM)"
Don't report TABLDISC - it "doesn't happen(TM)"