Avoid clearing some caches on save/load state

This should make loading and saving states faster.  A downside is that previously, saving state would clear the jit cache (possibly working around jit bugs), which it no longer does.

This also means saving state won't cause the display to blink.

With these changes, a "rewind" feature based on savestates becomes mostly possible.  I can only see it being practical on desktop, however, mostly due to memory requirements (and Snappy seems still too slow to run against such large data constantly.)

-[Unknown]