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)

RTC_TIMR's RTC_SEC field is BCD. That makes it unsuitable for
GetSeconds(). Instead, use CRTR register shifted right 15. This
gives us a range of 32 seconds we can do for timeout.

Shift to using == rather than < or > for calculating the timeout,
since if we can't read the ST_CTRT register twice in a second we have
even bigger problems to worry about, and == deals with the 'wrap'
issue.

This lets me type at the boot2 prompt again! Woo Hoo!

Bogusness noticed by: tisco
Pointy Hat to: That silly imp guy

MFp4:
Make getc(0) polling (this has the happy side effect of saving
8 bytes in the generated code).

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.