`fill-column` test should permit long package summary lines

[gonewest818]

package-lint suggests the package summary should be 60 characters or fewer. However, once you tack on a lexical binding declaration, what results is a line as long as 88 characters.

;;; dired-k.el --- Highlight dired by size, date, git status -*- lexical-binding: t; -*-

So the suggestion is to modify the fill-column test to allow just that initial line to be longer than fill-column as long as the line parses correctly as a package summary.