Merge remote-tracking branch 'remotes/ehabkost/tags/machine-next-pull-request' into staging

Machine queue, 2019-03-06

* qdev: Hotplug handler chaining (David Hildenbrand)
* qdev: fix qbus_is_full() (Tony Krowiak)
* hostmem: fix crash when querying empty host-nodes property via
  QMP (Igor Mammedov)

# gpg: Signature made Wed 06 Mar 2019 18:39:29 GMT
# gpg:                using RSA key 2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>" [full]
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/machine-next-pull-request:
  qdev: Provide qdev_get_bus_hotplug_handler()
  qdev: Let machine hotplug handler to override bus hotplug handler
  qdev: Let the hotplug_handler_unplug() caller delete the device
  hostmem: fix crash when querying empty host-nodes property via QMP
  qdev/core: fix qbus_is_full()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>