Re: master 6d4179957a8: Fix test of whether to insert lexical-binding cookies in custom files

[Eli Zaretskii]

> +            ;; The previous test `eobp' was written with an appalling
> +            ;; lack of forethought or testing, being easily misled if
> +            ;; the user should have left point at eob in a buffer
> +            ;; visiting the custom file.
> +            (when (eq (point-min) (point-max))

Is this test robust enough?  Why not use buffer-size instead?