It has long been assumed that host and guest architectures

It has long been assumed that host and guest architectures
are the same - even though the initial design goal was likely
different allowing a cross-valgrind of sorts. But as Julian
put it:
But it's been 12+ years and I've never once heard any mention of
such a thing.  So perhaps it's time to give up on that one.

Now let's take advantage of this decision and tighten up the VEX
API using Addr instead of Addr64. As a first step move the definition
of Addr into VEX proper and change the chase_into_ok callback
accordingly.

git-svn-id: svn://svn.valgrind.org/vex/trunk@3050