only call crossgcc for coreboot and u-boot, but use
hostcc for everything else. simplify the checking of
which architecture to compile for. "arch" in target.cfg
files has been modified, to allow further simplification.
without this patch, the logic currently only *barely* avoids
using crossgcc on things like utils, and only works in practise
because, in practise, lbmk only works on x86_64 anyway.
the new logic, as per this patch, is simpler and more robust.
Signed-off-by: Leah Rowe <leah@libreboot.org>
90ac30b163