Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix some nasty race conditions in the VIA-CUDA driver that ended up preventing
my right mouse button and keyboard LEDs from working due to mangled
configuration packets. Fixed several other races and associated problems in the
main ADB stack that were exposed while fixing this.

Fix some possible infinite loops in the ADB code, and remove some hacks
that were inserted in desperation during bring-up. In addition, move ADB bus
enumeration and child attachment to when interrupts are available.

Add ADB support. This provides support for the external ADB bus on the PowerMac
G3 as well as the internal ADB keyboard and mice in PowerBooks and iBooks. This
also brings in Mac GPIO support, for which we should eventually have a better
interface.

Obtained from: NetBSD (CUDA and PMU drivers)