empty such reference is 0, not nil.

These special cases were introduced in Go 1.10. For auto-updating code
from Go 1.9 and earlier, use the cftype or jni rewrites in the Go fix tool:

	go tool fix -r cftype <pkg>
	go tool fix -r jni <pkg>

It will replace nil with 0 in the appropriate places.

The EGLDisplay case was introduced in Go 1.12. Use the egl rewrite