[coreboot] kbuildall utility

[Patrick Georgi]

Hi,

attached file is a utility that generates default configs for all
boards, builds them, and keeps the config and build logs around and
creates a roster of all boards and their build status.

abuild does this for the newconfig based buildsystem, kbuildall does
this for kconfig/kbuild.

It's supposed to be put in the tree as util/kbuildall/kbuildall, and
called like that (ie. from the top level directory).

The results can be found in kbuildall.results/ in the toplevel
directory, the roster is called _overview.txt ("_" to make sure it's
sorted before or after all the board files)

Signed-off-by: Patrick Georgi