qemu_monitor: Introduce handler for 'query-current-machine' command
    
    So far, this command returns a structure with only one member:
    'wakeup-suspend-support'. But that's okay. It's what we are after
    anyway.
    
    Based-on-work-of: Daniel Henrique Barboza <danielhb413@gmail.com>
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>