This is mainly needed to handle the new control flow enforcement
extensions, making 3E a "notrack" prefix for indirect calls and jumps.
This is not (yet) modeled, and requires additional information on the
order of the prefixes, as 3E_66 (16-bit in ds segment) has a different
meaning than 66_3E (16-bit notrack). Before implementing this, an
analysis of the performance impact when decoding more prefix information
is probably required to avoid degrading overall performance for very few
and (as of now) seldomly used corner cases.
This allows to decode x86-32 machine code on a 64-bit platform (but
not vice versa). As a side-effect, we also get rid of pointer-size
detection for architecture selection.
