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)

Minor style(9) fixes for U-Boot API glue.

U-Boot API glue improvements:

- extend ub_dev_read() and ub_dev_recv() so that the actual len and
all error codes can be passed and processed properly; unify behaviour of
these routines

- introduce syscall general error code (API_ESYSC)

style(9) & style.Makefile(9)

Reviewed by: raj

Add the appropriate license information. This file is double
licensed under GPL and BSD.

Thanks to: raj@

MFp4 (e500):

Add support for U-Boot. This uses the U-Boot API as developed by
Rafal and which is (will be) part of U-Boot 1.3.2 and later.

Credits to: raj@