Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2018-12-18' into staging

QAPI patches for 2018-12-18

# gpg: Signature made Tue 18 Dec 2018 07:20:11 GMT
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <[email protected]>"
# gpg:                 aka "Markus Armbruster <[email protected]>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-qapi-2018-12-18:
  qapi: fix flat union on uncovered branches conditionals
  qmp hmp: Make system_wakeup check wake-up support and run state
  qga: update guest-suspend-ram and guest-suspend-hybrid descriptions
  qmp: query-current-machine with wakeup-suspend-support
  qmp: Split ShutdownCause host-qmp into quit and system-reset
  qmp: Add reason to SHUTDOWN and RESET events
  qapi: Turn ShutdownCause into QAPI enum

Signed-off-by: Peter Maydell <[email protected]>