bluez5: iso-io: add debug option for forcing same data in all streams

When debugging desync issues, it's useful to force same data be sent on
all ISO streams. Add option for that.

spa/plugins/bluez5/iso-io.h

@@ -35,6 +35,8 @@ struct spa_bt_iso_io
 	struct spa_audio_info format;	/**< Audio format */
 	void *codec_data;		/**< Codec data */
 
+	bool debug_mono;	/**< Duplicate packets from first sink to other sinks */
+
 	void *user_data;
 };