Fix 9patches' limitation of 32 empty quads

The 9patch format allows to define more empty quads than this, remove
the use of a single int to index empty quads and replace it with a
lookup in the 9patch resource data structure.

Change-Id: I148ee5d9e0c96822b534a344e15c9d88078db7c2
diff --git a/libs/hwui/Patch.h b/libs/hwui/Patch.h
index 246ba66..763a785 100644
--- a/libs/hwui/Patch.h
+++ b/libs/hwui/Patch.h
@@ -66,7 +66,7 @@
     void generateQuad(TextureVertex*& vertex, float x1, float y1, float x2, float y2,
             float u1, float v1, float u2, float v2, uint32_t& quadCount);
 
-    uint32_t mColorKey;
+    uint32_t* mColors;
     UvMapper mUvMapper;
 }; // struct Patch