O3: If there is an outstanding table walk don't let the inst queue sleep.

O3: If there is an outstanding table walk don't let the inst queue sleep.

If there is an outstanding table walk and no other activity in the CPU
it can go to sleep and never wake up. This change makes the instruction
queue always active if the CPU is waiting for a store to translate.

If Gabe changes the way this code works then the below should be removed
as indicated by the todo.