Fix T39607: Audio not in synch when the blend file loads.

The problem here was that animation buffers got initialized with zeros in the beginning for unknown parts. Now it gets initialized with the first known value.
The bug's result was that the animation of the pitch started with 0 on first playback and thus any seeking while the pitch is zero resulted in seeking to the beginning.

source/blender/blenkernel/intern/sound.c

@@ -566,8 +566,6 @@ void sound_play_scene(struct Scene *scene)
 			AUD_unlock();
 			return;
 		}
-
-		AUD_seek(scene->sound_scene_handle, cur_time);
 	}
 
 	if (status != AUD_STATUS_PLAYING) {