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)

$Id$ -> $FreeBSD$

Fixes for some style bugs in the initial version of this file:

- missing reformatting protection in copyright.
- missing blank line after copyright.
- unusual spelling of idempotency macro (no trailing underscore).
- unusual value of idempotency macro (1 instead of <empty>).
- space instead of tab after #define's.
- unnecessary namespace pollution and extra code to give it.
- tab instead of space after #endif.

Submitted by: bde

Fix short timeout problems with the pt(4) driver:

- increase the default timeout from 10 seconds to 60 seconds
- add a new kernel option, SCSI_PT_DEFAULT_TIMEOUT, that lets users specify
the default timeout for the pt driver to use
- add two new ioctls, one to get the timeout for a given pt device, the
other to set the timeout for a given pt device. The idea is that
userland applications using the device can set the timeout to suit their
purposes. The ioctls are defined in a new header file, sys/ptio.h

PR: 10266
Reviewed by: gibbs, joerg