egl: Add EGL extension for front buffer auto-refresh mode

- Add an EGL extension for enabling/disabling auto-refresh mode on
  a surface that's being used for front-buffer rendering.
- Remove the temporary hack that was directly enabling/disabling
  front-buffer rendering from the EGL wrapper. From now on the driver
  will have to implement it.

Bug 24949410

Change-Id: I722577521a37f9892dbadaf504b4551fe37182ed
diff --git a/opengl/include/EGL/eglext.h b/opengl/include/EGL/eglext.h
index 267f8af..5d838e6 100644
--- a/opengl/include/EGL/eglext.h
+++ b/opengl/include/EGL/eglext.h
@@ -611,6 +611,12 @@
 #endif
 #endif
 
+#ifndef EGL_ANDROID_front_buffer_auto_refresh
+#define EGL_ANDROID_front_buffer_auto_refresh 1
+#define EGL_FRONT_BUFFER_AUTO_REFRESH_ANDROID 0x314C
+#endif
+
+
 #ifdef __cplusplus
 }
 #endif