Clear framebuffers/textures upon sceKernelLoadExec()

I'm thinking this is at least related to #6432.  From a log, it uses sceKernelLoadExec()... and we were not clearing FBOs or etc.  I'm worried something was getting stuck, and the best way is to just clear it.

Also reverts the io stuff.  We know io is not as fast as we make it, so waking early there doesn't actually make sense.  If it causes bugs, removing it seems fine.

-[Unknown]