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

Change-Id: Iee4e9df37d4c971ea97256d041afbc3d3aaa3d27
Reviewed-on: https://gerrit.libreoffice.org/70027
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>