Add a render buffer cache to reuse stencil buffers
Bug #7146141

This new cache is used in a similar way to LayerCache. It helps
reuse already allocated stencil buffers and thus avoid churning
memory on every frame.

Change-Id: I19551d72da52c40039e65904563600e492c8b193
diff --git a/libs/hwui/Caches.h b/libs/hwui/Caches.h
index 0fa54fb..d70c0e3 100644
--- a/libs/hwui/Caches.h
+++ b/libs/hwui/Caches.h
@@ -29,6 +29,7 @@
 #include "GammaFontRenderer.h"
 #include "TextureCache.h"
 #include "LayerCache.h"
+#include "RenderBufferCache.h"
 #include "GradientCache.h"
 #include "PatchCache.h"
 #include "ProgramCache.h"
@@ -249,6 +250,7 @@
 
     TextureCache textureCache;
     LayerCache layerCache;
+    RenderBufferCache renderBufferCache;
     GradientCache gradientCache;
     ProgramCache programCache;
     PathCache pathCache;