The constructor sets up way_from_valid and way_from_plur as fast lookup
tables for implementing the PLRU algrothm. Then the Init function
memsets them to zero, meaning the instruction cache will now always
choose the first way in each set.
This degrades the cache from 128 sets, 8 way to 128 sets, 1 way.
Not only does fixing this bug increase accuracy, but it increases
preformance too, giving a 1% speedup to interpreter.
The PowerPC CPU has bits in MSR (DR and IR) which control whether
addresses are translated. We should respect these instead of mixing
physical addresses and translated addresses into the same address space.
This is mostly mass-renaming calls to memory accesses APIs from places
which expect address translation to use a different version from those
which do not expect address translation.
This does very little on its own, but it's the first step to a correct BAT
implementation.
