…disable memcache support
Previously this would attempt to wait on an empty pollset if the user for some reason set `deaf=no` without configuring a UDP receive channel. This would lead (on Linux) to a tight loop calling `epoll_wait` which immediately failed with `EINVAL` as we provided no fds to wait on. This resulted in high CPU usage.
This adds the "condrestart" subcommand, which is needed to restart the ganglia daemons in the rpm %postun scriptlet.