Note: While this is technically an ABI change I believe it is a
change that we can afford at this time (and to be pulled up to
2.0, which will be the first release for amd64). The types are
not widely used yet, and a survey of pkgsrc has not shown uses
that would be adversely affected by it.
the processor family now. x86_64 is kept as the MACHINE_ARCH value,
since it's already widely used (by e.g. the toolchain, etc), and
by other operating systems.
