As a complementer to clang-tidy-12 --checks="-*,misc-unused-using-decls"
Pros:
- simple, fast!
- finds some more unused declarations, somehow
- works on non-linux specific parts of the code
- clang-tidy (for me) trips on files with external headers, this does not
Change-Id: If2db989114ac5c2841ed2e89ff7bd7a9e419f567
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/150612
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
