Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2020-03-17' into staging

QAPI patches for 2020-03-17

# gpg: Signature made Tue 17 Mar 2020 20:50:54 GMT
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-qapi-2020-03-17: (30 commits)
  net: Track netdevs in NetClientState rather than QemuOpt
  net: Complete qapi-fication of netdev_add
  qmp: constify QmpCommand and list
  qapi: Mark deprecated QMP parts with feature 'deprecated'
  qapi: New special feature flag "deprecated"
  qapi: Replace qmp_dispatch()'s TODO comment by an explanation
  qapi: Simplify how qmp_dispatch() gets the request ID
  qapi: Simplify how qmp_dispatch() deals with QCO_NO_SUCCESS_RESP
  qapi: Inline do_qmp_dispatch() into qmp_dispatch()
  qapi: Add feature flags to struct members
  qapi/schema: Call QAPIDoc.connect_member() in just one place
  qapi/schema: Rename QAPISchemaObjectType{Variant,Variants}
  qapi/schema: Reorder classes so related ones are together
  qapi/schema: Change _make_features() to a take feature list
  qapi/introspect: Factor out _make_tree()
  qapi/introspect: Rename *qlit* to reduce confusion
  qapi: Consistently put @features parameter right after @ifcond
  qapi: Add feature flags to remaining definitions
  qapi/schema: Clean up around QAPISchemaEntity.connect_doc()
  tests/test-qmp-event: Check event is actually emitted
  ...

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