Add 'info memory_size_summary' command which is a sibling
of QMP command query-memory-size-summary. It provides the
following memory information in bytes:

  * base-memory - size of "base" memory specified with command line option -m.

  * plugged-memory - amount of memory that was hot-plugged.
    If target does not have CONFIG_MEM_HOTPLUG enabled, no
    value is reported.

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Signed-off-by: Mohammed Gamal <mohammed.gamal@profitbricks.com>
Signed-off-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>
Signed-off-by: Vadim Galitsyn <vadim.galitsyn@profitbricks.com>
Reviewed-by: Eugene Crosser <evgenii.cherkashin@profitbricks.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: qemu-devel@nongnu.org
Message-Id: <20170829153022.27004-4-vadim.galitsyn@profitbricks.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  Fixed up comments from Igor's review