Shouldn't be necessary to flush on drawsync.
Fix threadsafe event removal.
Use threadsafe events for GE communication.

Hopefully this doesn't cause problems again for 3rd Birthday or FF Type-0.
Kinda need it.
Schedule ts events using the same time frame.
Treat savestates specially, no longer using events.

This makes it easier to run them on the GPU thread anyway, which is best
if they reset GPU caches etc., and should remove any timing related
issues.
Get rid of CoreTiming::AdvanceQuick().

It basically existed for savestates, so no longer needed.
Fixes issues with events not running when they should.
Enable interrupts as a property of the list.

This way there's no behavior change when enqueue is async.
Merge pull request #3075 from unknownbrackets/gpu-thread

Prep work for GE and CPU on separate threads