EGL: add the native_fence_sync extension

This change adds support for the EGL_ANDROID_native_fence_sync extension to the
Android EGL layer.  It also fixes a couple minor issues with the extension spec.

Change-Id: Ic8829d21f37b701f33aa9c72c3d25e88e03fa3cd
diff --git a/opengl/libs/EGL/egl_display.cpp b/opengl/libs/EGL/egl_display.cpp
index 80072ab..371df43 100644
--- a/opengl/libs/EGL/egl_display.cpp
+++ b/opengl/libs/EGL/egl_display.cpp
@@ -59,6 +59,7 @@
 // extensions not exposed to applications but used by the ANDROID system
 //      "EGL_ANDROID_recordable "               // mandatory
 //      "EGL_ANDROID_blob_cache "               // strongly recommended
+//      "EGL_ANDROID_native_fence_sync "        // strongly recommended
 //      "EGL_IMG_hibernate_process "            // optional
 
 extern void initEglTraceLevel();