The -mon pretty=on|off switch of the -mon option applies only to QMP
monitors. It's silently ignored for HMP. Deprecate this combination so
that we can make it an error in future versions.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20190613153405.24769-16-kwolf@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>