This package builds the representation of the machine architecture
for the new assembler.
Almost nothing in it is likely to last but this will get things running.
Change-Id: I8edd891f927a81f76d2dbdcd7484b9c87ac0fb2e
Reviewed-on: https://go-review.googlesource.com/3194
Reviewed-by: Russ Cox <rsc@golang.org>
