timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.
The old timeout()/untimeout() API has been removed from the kernel.
interface border, so that other serial interfaces can be attached to the
ms/kbd. zero functional changes and mostly involves moving code around
a bit. tested on the SS2.
this is necessary to attach the PCI ultrasparc keyboard/mouse drivers.