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

* remotes/qmp-unstable/queue/qmp:
  qapi: zero-initialize all QMP command parameters
  scripts/qapi.py: Avoid syntax not supported by Python 2.4
  doc: add "setup" to list of migration states

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