libsaria: Remove old function declarations

I replaced these functions with a self-contained class.  I don't need to
keep these around anymore.

include/libsaria/audio.h

@@ -30,8 +30,4 @@ class Audio
 		void seek();
 };
 
-void audio_init(int, char **);
-void gst_play();
-void gst_pause();
-
 #endif /* LIBSARIA_AUDIO_H */