The compiler should produce reasonable code here in general, so punt the
various arch checks and bswap defines. This code will eventually go away
entirely when we convert it to the common memory code.
By itself, this commit doesn't really change anything. It lays the
groundwork for using the cpu state in follow up commits, both for
engine state and for cpu state. Splitting things up this way so it
is easier to see how things have changed.
