ALSA: default normally includes plug, don't add it again

This should work around distortion problems with some cards (probably
an ALSA-lib bug).

modules/audio_output/alsa.c

@@ -85,7 +85,7 @@ struct aout_sys_t
 /* Why not ? --Bozo */
 /* Right. --Meuuh */
 
-#define DEFAULT_ALSA_DEVICE "plug:default"
+#define DEFAULT_ALSA_DEVICE "default"
 
 /*****************************************************************************
  * Local prototypes