The queue for saving chunk data is specified by GSChunkStore.
Bug with GSChunkStore's countdown till the next chunk update is fixed.
Don't bother making the filedes non-blocking before calling close.

There doesn't seem to be much of a benefit to doing this.
Getting rid of GSChunkStore's periodic chunk update.

This doesn't really do much good. Might as well try to update every frame.
Locking to safely enumerate active region. Fixes flashing screen bug.

Sometimes, the screen would flash when visibility computations and drawing
were being done at the same time, and chunks which should have been visible
failed to be drawn. This change fixes that problem by locking the active
region while enumerating chunks druing these operations.