Set lastTime to zero.

Shouldn't be different from the constructor.

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/AnimationState.java

@@ -312,7 +312,7 @@ public class AnimationState {
 			animation = null;
 			listener = null;
 			timeScale = 1;
-			lastTime = -1;
+			lastTime = 0;
 			time = 0;
 		}