FramebufferNativeWindow.h is obsolete

This adds a deprecation #warning to the header.

Change-Id: Ia32f16e491cb01d435ec8846dda3d9a7d1a9cfc5
diff --git a/include/ui/FramebufferNativeWindow.h b/include/ui/FramebufferNativeWindow.h
index 5ec738f..5cd8101 100644
--- a/include/ui/FramebufferNativeWindow.h
+++ b/include/ui/FramebufferNativeWindow.h
@@ -17,6 +17,8 @@
 #ifndef ANDROID_FRAMEBUFFER_NATIVE_WINDOW_H
 #define ANDROID_FRAMEBUFFER_NATIVE_WINDOW_H
 
+#warning "FramebufferNativeWindow is deprecated"
+
 #include <stdint.h>
 #include <sys/types.h>