On Red Hat 7+ and derived distributions, 'nc' is nmap-ncat, but on
Debian based distributions this is often netcat-openbsd.  Both are
mostly compatible with the important distinction that netcat-openbsd
does not shutdown the socket on stdin EOF without also passing '-N' as
an argument which is not supported on nmap-ncat.  This has the
unfortunate consequence of hanging qmp calls so tests like aarch64
its-migration never complete.

We're depending on ncat behaviour and nmap-ncat is available in all
major distributions.

Signed-off-by: Jamie Iles <jamie@nuviainc.com>
Message-Id: <20200921103644.1718058-1-jamie@nuviainc.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>