add FU write-after-write hazard detection Signal (dummy so far)

add FU write-after-write hazard detection Signal (dummy so far)

this has to be set up in the connect_write section but then
*used* in connect_rdport in order to stop reading from happening

strictly speaking it should actually stop issue, but we already
established that that way lies madness (combinatorial loops).

this may turn out to be a bit more complex than initially planned
due to some instructions potentially not having read at all
(only write)