[SDL] Buggy SB Live - Fixed

[Sam Lantinga]

> It seems the problem with the SB Live, or at least the problem that
> affected our game, was that the drivers are somewhat high latency.
> Therefore, increasing the mixer chunk_size from 1024 to 3072 solves
> the problem (althoug it introduces some latency, of course!)

How about 2048?  Some audio drivers require the chunk size to be a power of 2.

See ya!
	-Sam Lantinga, Software Engineer, Blizzard Entertainment