Create one hole inside the umbra area to avoid overdraw.

bug:13439450

Change-Id: I859575196bd5a3029f447883025a6ec3a1f1face
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index 94abfa7..059c64f 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -119,7 +119,8 @@
 
 enum VertexBufferMode {
     kVertexBufferMode_Standard = 0,
-    kVertexBufferMode_Shadow = 1
+    kVertexBufferMode_OnePolyRingShadow = 1,
+    kVertexBufferMode_TwoPolyRingShadow = 2
 };
 
 ///////////////////////////////////////////////////////////////////////////////