[sdlsound] playsound crash (PhysicsFS-related)

[Ryan C. Gordon]

> This is because PHYSFS_deinit() is being called without a corresponding
> call to PHYSFS_init(). I think the actual crash happens because
> PhysicsFS's findErrorForCurrentThread() tries to grab the errorLock
> mutex, which hasn't been created at this stage.

This is due to cruddy behaviour in both physfs and playsound. I've fixed
both in CVS, now.

Thanks,
--ryan.