Don't clear the GPU caches on savestate, just load.

And maybe it's not even fully necessary on load...
Avoid clearing the jit cache on savestate.

Downside: saving state could "fix" some issues with games detecting jit,
which won't happen anymore.

However, it's now faster to savestate.
Separate a quick interface to savestate to memory.
Merge pull request #3989 from unknownbrackets/savestates

Avoid clearing some caches on save/load state