Prevent receive extra callbacks from AnimatorListener.

There will receive another onAnimationStart/onAnimationEnd callback
when calling ValueAnimator#end if the animation is not running, which
is not necessary if the animation was finished already.

Bug: 195736656
Test: atest SplashscreenTests
Change-Id: Ifbbf2f799e3e69624626b16e08f40b562fe483a8

libs/WindowManager/Shell/src/com/android/wm/shell/startingsurface/SplashscreenIconDrawableFactory.java

@@ -314,7 +314,7 @@ public class SplashscreenIconDrawableFactory {
 
         @Override
         public void stopAnimation() {
-            if (mIconAnimator != null) {
+            if (mIconAnimator != null && mIconAnimator.isRunning()) {
                 mIconAnimator.end();
             }
         }