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.cpp b/libs/hwui/TextureCache.cpp
index 460284e..612f04e 100644
--- a/libs/hwui/TextureCache.cpp
+++ b/libs/hwui/TextureCache.cpp
@@ -28,7 +28,7 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 TextureCache::TextureCache(uint32_t maxByteSize):
-        mCache(GenerationSingleCache<SkBitmap*, Texture*>::kUnlimitedCapacity),
+        mCache(GenerationCache<SkBitmap*, Texture*>::kUnlimitedCapacity),
         mSize(0), mMaxSize(maxByteSize) {
     mCache.setOnEntryRemovedListener(this);
 }