Removing sys/boot/arm/at91 and sys/boot/arm/ixp425

[Warner Losh]

I'd like to remove sys/boot/arm/at91 (bootstrap code for the AT91RM9200
that works on a couple of reference boards, but not universally) and
sys/boot/arm/ixp425 (which is for Gateworks Cambria 235x and Avila 2348
boards).

The AT91 boot stuff is likely better served by Atmel's AT91Bootstrap +
uboot. The at91 stuff likely hasn't been tested in several years, though I
know one company that uses a modified version with FreeBSD 8... It's been
disconnected from the build forever. It does still build though. I have no
clue if it works owing to the difficulty in tweaking it just so to work on
the AT91RM9200 gear I still have left. This was always a super specialized
build, and perhaps shouldn't have been committed in the first place given
how the AT91SAM9 line evolved (its SRAM size shrank to 4k, making it simply
impossible to fit).

The ixp425 doesn't build, and likely hasn't for a while (there's undefined
references to memset, despite trying to avoid such references). It needs to
be reworked to support the current tree layout (even before my changes to
libstand) and compiler technologies. This is for the Intel IXP 425
processors found on the Gateworks Avila and Cambria boards. They were
released in 2006 and EOLd by intel in 2009. Redboot is a possible
alternative. We don't create releases for it, and it's not otherwise
referenced in the tree.

Absent any real users that would be affected by these boot loaders, I'd
like to just remove them from the tree rather than try to fix them up an
modernize them and/or include them in the builds so breakage is discovered
sooner...

Comments?

Warner