set up for the amd64/amd64 TARGET/TARGET_ARCH combination.
Some of the build tools used here (u-boot in particular) require
use of gcc(1). The lang/gcc* from ports/ will install as 'gccNN'
instead of 'gcc', so they cannot be used without extra hacks.
Add an EMBEDDED_WORLD_FLAGS variable to be used to properly set
up the build chroot. For the RPI-B case, EMBEDDED_WORLD_FLAGS
is set to 'WITH_GCC=1', which is used to set up the build chroot.
While here, in followup to r260895, do not rely on the necessary
configuration files and/or scripts to exist in the build target
src/ tree.
To work around cases where files do not exist, copy (from the
local release/ checkout) the tools/${XDEV}/crochet-${KERNEL}.conf
to ${CHROOTDIR}/tmp/external/crochet-${KERNEL}.conf to make them
accessible to the external utilities that need them (i.e., crochet).
Sponsored by: The FreeBSD Foundation
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