SIGUSR2 for reopening log files was handled by ZServer and waitress does not
handle signals at all, so we could handle this signal but Zope official
documentation recommends using logrotate `copytruncate`:
  https://zope.readthedocs.io/en/4.7/zopebook/MaintainingZope.html#log-rotation
  https://github.com/zopefoundation/Zope/issues/809