Remove unnecessary GL calls.

This change batches calls to glScissor() and removes extra GL
queries and glActiveTexture() calls.

Change-Id: I1cd079d314f87cd9c088f95c8d4909c2f860f6aa
diff --git a/libs/hwui/Caches.h b/libs/hwui/Caches.h
index aff5366..ca22867 100644
--- a/libs/hwui/Caches.h
+++ b/libs/hwui/Caches.h
@@ -23,6 +23,7 @@
 
 #include <utils/Singleton.h>
 
+#include "Extensions.h"
 #include "FontRenderer.h"
 #include "GammaFontRenderer.h"
 #include "TextureCache.h"
@@ -93,8 +94,15 @@
     GLenum lastDstMode;
     Program* currentProgram;
 
+    // VBO to draw with
     GLuint meshBuffer;
 
+    // GL extensions
+    Extensions extensions;
+
+    // Misc
+    GLint maxTextureSize;
+
     TextureCache textureCache;
     LayerCache layerCache;
     GradientCache gradientCache;