This option reduces the number of wires that cross the clock boundary.
This can be a useful feature if the clock boundary coincides with
a voltage boundary, in which case the number of level shifters is reduced.
However, this introduces a path that crosses from sink->source->sink domain,
so the option is disabled by default.
This addresses a bug in which changes in mstatus could
propagate to RoCCs before their time. Existing RoCCs that use
the status port will need to be modified to match this change.
This addresses the first half of #40.
Ben KellerandHenry Cook
