Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add locking to the ahb(4) driver and mark it MPSAFE.
- Use device_printf() and device_get_unit() instead of storing the unit
number in the softc.
- Remove use of explicit bus space handles and tags.
- Compare pointers against NULL.
- Let new-bus allocate a softc rather than doing it by hand.

Tested by: no one

Prepare for future integration between CAM and newbus. xpt_bus_register
now takes a device_t to be the parent of the bus that is being created.
Most SIMs have been updated with a reasonable argument, but a few exceptions
just pass NULL for now. This argument isn't used yet and the newbus
integration likely won't be ready until after 7.0-RELEASE.

Start each of the license/copyright comments with /*-, minor shuffle of lines

Back out the previous change to the queue(3) interface.
It was not discussed and should probably not happen.

Requested by: msmith and others

Change the way that the queue(3) structures are declared; don't assume that
the type argument to *_HEAD and *_ENTRY is a struct.

Suggested by: phk
Reviewed by: phk
Approved by: mdodd

$Id$ -> $FreeBSD$

Adaptec 174x EISA SCSI Host Adapter driver for CAM.