Use AutoScrollHelper from the support-v4 library

Bug: 10532260
Change-Id: Ic6519a119fd75890c766b6ffccfc5f660934e1b7
diff --git a/src/com/android/launcher3/FolderAutoScrollHelper.java b/src/com/android/launcher3/FolderAutoScrollHelper.java
index 3c2b449..40e8884 100644
--- a/src/com/android/launcher3/FolderAutoScrollHelper.java
+++ b/src/com/android/launcher3/FolderAutoScrollHelper.java
@@ -16,6 +16,7 @@
 
 package com.android.launcher3;
 
+import android.support.v4.widget.AutoScrollHelper;
 import android.widget.ScrollView;
 
 /**