[coreboot] debugging symbols for final ROM image

[ron minnich]

I like the idea of the bios always being debuggable. Proprietary
bios'es strip this info out, of course, and in a lot of cases you can
learn a lot if you just have the symbol names.

It has to fit, however. Or we can make a symbol file available on the
web site for each known good board build. I.e., you want to walk
through some code, you wget the symbol file and use it to examine your
in-flash coreboot image.

ron