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)

MFp4: Update to smaller code footprint.

MFp4: First cut at making spi and/or sd card booting work, needs work

MFp4 (checkpoint of work in progress):

o Use a directory layout that is more akin to the i386 boot layout.
o Create a libat91 for library routines that are used by one or more
of the boot loaders.
o Create bootiic for booting from an iic part.
o Create bootspi for booting from an spi part.
o Optimize the size of many of these routines (especially emac.c). Except
for the emac.c optimizations, all these have been tested.
o eliminate the inc directory, libat91 superceeds it.
o Move linker.cfg up a layer to allow it to be shared.