Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2019-03-05' into staging

QAPI patches for 2019-03-05

# gpg: Signature made Tue 05 Mar 2019 16:47:17 GMT
# gpg:                using RSA key 3870B400EB918653
# 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-2019-03-05:
  qapi: Fix array first used in a different module
  tests/qapi-schema: Cover forward reference to sub-module
  tests: Rename UserDefNativeListUnion to UserDefListUnion
  qapi: Fix code generation for sub-modules in other directories
  qapi: Pass file name to QAPIGen constructor instead of methods
  tests/qapi-schema: Cover conditional arrays
  tests/qapi-schema: Make test-qapi.py print arrays

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