Optimize 9patch rendering.

This change detects empty quads in 9patches and removes them from
the mesh to avoid unnecessary blending.

Change-Id: I4500566fb4cb6845d64dcb59b522c0be7a0ec704
diff --git a/libs/hwui/Matrix.cpp b/libs/hwui/Matrix.cpp
index 219fd5e..5502e66 100644
--- a/libs/hwui/Matrix.cpp
+++ b/libs/hwui/Matrix.cpp
@@ -24,6 +24,7 @@
 
 #include <SkMatrix.h>
 
+#include "utils/Compare.h"
 #include "Matrix.h"
 
 namespace android {
@@ -53,9 +54,6 @@
     mSimpleMatrix = true;
 }
 
-#define EPSILON 0.00001f
-#define almost(u, v) (fabs((u) - (v)) < EPSILON)
-
 bool Matrix4::changesBounds() {
     return !(almost(data[0], 1.0f) && almost(data[1], 0.0f) && almost(data[2], 0.0f) &&
              almost(data[4], 0.0f) && almost(data[5], 1.0f) && almost(data[6], 0.0f) &&