build: build everything as external projects.

This gets the dependencies correct - we need binutils before bootrom and
tests.
Revert "build: build everything as external projects."

Move binutils-oldland outside of this tree, we'll just build it before
and have a super project to build everything.  Eventually toolchain
stuff can go in openembedded.

This reverts commit 51647f62f44940d8d401d5ae0cb1743aeb33effc.