cpp11-migrate: Add override specifier before comments on inline methods

This commit fixes a "FIXME" in the add-override transform. ' override' was
misplaced when a comment was between the function body and the end of the
'prototype'.

It also remove duplicated check for the main file from the last commit (and
fixes the typo in the comment above).

Author: Guillaume Papin <guillaume.papin@epitech.eu>