Found with:
run-clang-tidy-7 -checks=-*,misc-unused-using-decls

Change-Id: I50f6dfa881ac4e752668e762ade0943aaf28ab96
Reviewed-on: https://gerrit.libreoffice.org/69601
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>