[prey] Crackling Sound issue work-around (for PA)

[Ryan C. Gordon]

> If you dare, you can modify the launcher script in $PREY_INSTALL_PATH/ 
> prey, and somwehere at the top of the file (bellow the first comments, 
> for example) append:
> 
> export SDL_AUDIODRIVER=pulseaudio

The retail version (and updated demo) uses PulseAudio by default, if it 
sees the pulse daemon running, so there's no need to do this, except for 
the original demo, which used /dev/dsp as the default.

Failing that, it will try ALSA, and failing that, it will try /dev/dsp.

--ryan.