Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

* remotes/qmp-unstable/queue/qmp:
  Add HMP command "info memory-devices"
  qemu-socket: Eliminate silly QERR_ macros
  qemu-socket: Polish errors for connect() and listen() failure
  qemu-iotests: Test missing "driver" key for blockdev-add
  tests: add QMP input visitor test for unions with no discriminator
  qapi: dealloc visitor, implement visit_start_union
  qapi: add visit_start_union and visit_end_union
  virtio-balloon: fix integer overflow in memory stats feature
  monitor: Reset HMP mon->rs in CHR_EVENT_OPEN

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