[LINTER] Check for header guard closure comment
This enforces setting the header guard as a comment following the
Includes the fix for the header files violating the rule.
Should return nothing:
arc lint --everything
Remove the comment of an header guard and check the linter catches it.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D4218