Implement suspend/resume HLE for threads

I only have three games that actually hit these functions, and none of them seem to mind this implementation.  I also have a test for it, but I'm not sure if I'm missing anything...

That said, I don't know of any games this helps and I don't feel it's extensively tested... maybe if someone could try this on a few other games (specifically these: http://report.ppsspp.org/temp/recent/kind/68) it might be good before merging.

Applies on top of my other scheduling pull, since it hit conflicts splitting them...

-[Unknown]