[unity] Remove old code.

spine-unity/Assets/spine-unity/Modules/SkeletonGraphic/BoneFollowerGraphic.cs

@@ -113,12 +113,7 @@ namespace Spine.Unity {
 
 				if (followBoneRotation) {
 					Vector3 worldRotation = skeletonTransform.rotation.eulerAngles;
-					#if UNITY_5_6_OR_NEWER
 					thisTransform.SetPositionAndRotation(targetWorldPosition, Quaternion.Euler(worldRotation.x, worldRotation.y, skeletonTransform.rotation.eulerAngles.z + boneWorldRotation));
-					#else
-					thisTransform.position = targetWorldPosition;
-					thisTransform.rotation = Quaternion.Euler(worldRotation.x, worldRotation.y, skeletonTransform.rotation.eulerAngles.z + bone.WorldRotationX);
-					#endif
 				} else {
 					thisTransform.position = targetWorldPosition;
 				}