When making 92d1d60, I checked whether the ~0x1f masking in dcbx
actually was necessary. I came to the conclusion that it wasn't,
so I removed it. However, I hadn't checked the second half of
InvalidateICache closely enough - the masking is actually needed.
This commit re-adds the masking, but this time in C++ code instead
of in jitted code in order to save icache. Though I suppose the
difference doesn't matter all that much, since this is in farcode
and all...
Hopefully fixes https://bugs.dolphin-emu.org/issues/12612.
125af42e4b