If a frame callback is not destroyed when destroying a surface, its
handler function will be invoked if the surface was destroyed after the
callback was requested but before it was invoked, causing a write on
free:ed memory.
This can happen if eglDestroySurface() is called shortly after
eglSwapBuffers().
Note: This is a candidate for stable branches.
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>