Cleanup of FontRenderer

Remove invalid and over complicated buffer unbinding
optimization, and simplify constructor.

Change-Id: I3dd90528de4f377e972bbd7967e7e232875387e4
diff --git a/libs/hwui/OpenGLRenderer.h b/libs/hwui/OpenGLRenderer.h
index 63a63b8..e1bef65 100755
--- a/libs/hwui/OpenGLRenderer.h
+++ b/libs/hwui/OpenGLRenderer.h
@@ -677,7 +677,7 @@
      * are transformed with the supplied matrix.
      */
     void dirtyLayer(const float left, const float top,
-            const float right, const float bottom, const mat4 transform);
+            const float right, const float bottom, const Matrix4& transform);
 
     /**
      * Mark the layer as dirty at the specified coordinates.