BootAnimation: Avoid memory leak in error case

If we fail preloadZip(), we release the animation prior to
returning.

Test: TreeHugger
Change-Id: I632c052ef22b2a7192b516de5726bf4e74544f7a

cmds/bootanimation/BootAnimation.cpp

@@ -1157,6 +1157,7 @@ BootAnimation::Animation* BootAnimation::loadAnimation(const String8& fn)
 
     parseAnimationDesc(*animation);
     if (!preloadZip(*animation)) {
+        releaseAnimation(animation);
         return nullptr;
     }