Declare -realtime as deprecated

Declare -realtime as deprecated

The old -realtime mlock=on|off parameter does exactly the same as the
new -overcommit mem-lock=on|off parameter. Additionally, "-realtime"
does not activate any additional "realtime" capabilities as the name
might indicate. We should avoid to confuse the users this way, so
let's deprecate the old -realtime option.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190411175345.19414-1-thuth@redhat.com>