Clean up libEGL.def. BUG=angle:490 Change-Id: I6f0f707862066c9906aa38601aa6839b78a5cc39 Reviewed-on: https://chromium-review.googlesource.com/204565 Reviewed-by: Brandon Jones <bajones@chromium.org> Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>