Set cache dirty when re-create the cache bitmap

b/17503595

Change-Id: Icdaa3651345b740772363f8afb29bb36741fcc87

graphics/java/android/graphics/drawable/VectorDrawable.java

@@ -702,6 +702,7 @@ public class VectorDrawable extends Drawable {
                     bounds.height())) {
                 mCachedBitmap = Bitmap.createBitmap(bounds.width(), bounds.height(),
                         Bitmap.Config.ARGB_8888);
+                mCacheDirty = true;
             }
 
         }