Comment 4 for bug 1905356

Because for user-only, we cheat and use host load/store
operations directly. This makes for much faster emulation
but imposes a number of limitations -- including ignoring
of the alignment bits on hosts that have native unaligned
accesses.

As a corollary, when running user-only on a host that
enforces alignment, you cannot emulate a guest that
*allows* unaligned accesses.