Add missing public native API

Change-Id: Ie3bc706b2ac91d686a5b888e8ae841820e9d37c7
diff --git a/libs/hwui/Matrix.h b/libs/hwui/Matrix.h
index 56fd37d..22220a9 100644
--- a/libs/hwui/Matrix.h
+++ b/libs/hwui/Matrix.h
@@ -19,6 +19,8 @@
 
 #include <SkMatrix.h>
 
+#include <cutils/compiler.h>
+
 #include "Rect.h"
 
 namespace android {
@@ -28,7 +30,7 @@
 // Classes
 ///////////////////////////////////////////////////////////////////////////////
 
-class Matrix4 {
+class ANDROID_API Matrix4 {
 public:
     float data[16];