scripts: build cbutils, not specific utils

some checks check for specific utils, which are
then used to indicate the existence of other utils,
which means that building them singularly, as is
currently done, may result in errors later if another
tool doesn't exist compiled yet

this is an obscure bug, fixed by this patch. more of a
workaround really. a dirty hack. when checking for any
of the coreboot utilities required, build all coreboot
utilities that are possibly required

the utilities are small enough that this does not add
much extra time to build, and in most cases, all of them
will be needed anyway