remove dependency of EGL on ndk header

Change-Id: Ia6e489b5b4f028864bdf54923e81f604710dd8ad
diff --git a/include/gui/SurfaceTextureClient.h b/include/gui/SurfaceTextureClient.h
index 1051bd2..f86e8fd 100644
--- a/include/gui/SurfaceTextureClient.h
+++ b/include/gui/SurfaceTextureClient.h
@@ -27,6 +27,8 @@
 #include <utils/RefBase.h>
 #include <utils/threads.h>
 
+struct ANativeWindow_Buffer;
+
 namespace android {
 
 class Surface;