'memtotal' in virtio drivers and qemu corresponds to 'available' in libvirt.
Because of that, 'stat-available-memory' is renamed into 'usable'.
Balloon statistics are not reported in hrf, so no modifications are made in qemu_monitor_text.c.
Signed-off-by: Derbyshev Dmitry <dderbyshev@virtuozzo.com>
