Without this, the PulseAudio output is completely useless. PulseAudio
provides ALSA emulation, so VLC would always use ALSA. Now, it will use
ALSA if PulseAudio is not available, but avoid the PulseAudio ALSA
emulation which makes more sense. Either way, if your PulseAudio setup
is broken, you are screwed - this change makes no difference.