Revert "Simplify projection matrix management."

This reverts commit 0efaa71d5414287ed4beac0a88cf76f7e33a1e74.
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index d140428..4f7f01e 100644
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -930,6 +930,9 @@
      */
     Texture* getTexture(const SkBitmap* bitmap);
 
+    // Ortho matrix used for projection in shaders
+    mat4 mProjectionMatrix;
+
     /**
      * Model-view matrix used to position/size objects
      *