Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2019-10-22-v3' into staging

Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2019-10-22-v3' into staging

QAPI patches for 2019-10-22

# gpg: Signature made Tue 22 Oct 2019 15:56:36 BST
# 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-2019-10-22-v3:
  qapi: Allow introspecting fix for savevm's cooperation with blockdev
  tests/qapi-schema: Cover feature documentation comments
  tests: qapi: Test 'features' of commands
  qapi: Add feature flags to commands
  tests/qapi-schema: Tidy up test output indentation
  qapi: Clear scripts/qapi/doc.py executable bits again
  qapi: Split up scripts/qapi/common.py
  qapi: Move gen_enum(), gen_enum_lookup() back to qapi/types.py
  qapi: Speed up frontend tests
  qapi: Eliminate accidental global frontend state
  qapi: Store pragma state in QAPISourceInfo, not global state
  qapi: Don't suppress doc generation without pragma doc-required

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