Simpler way to deal with the FBO multi-cache.

This change removes the need for the SortedList and instead just
add a generated id to each FBO stored in the cache. This is an
artificial way to store several FBOs with the same dimensions.

Change-Id: I9638364e9bdc0f2391261937a0c86096f20505bf
diff --git a/libs/hwui/TextureCache.h b/libs/hwui/TextureCache.h
index a620876..bed1191 100644
--- a/libs/hwui/TextureCache.h
+++ b/libs/hwui/TextureCache.h
@@ -78,7 +78,7 @@
      */
     void generateTexture(SkBitmap* bitmap, Texture* texture, bool regenerate = false);
 
-    GenerationSingleCache<SkBitmap*, Texture*> mCache;
+    GenerationCache<SkBitmap*, Texture*> mCache;
 
     uint32_t mSize;
     uint32_t mMaxSize;