Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2016-05-12' into staging

Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2016-05-12' into staging

QAPI patches for 2016-05-12

# gpg: Signature made Thu 12 May 2016 08:49:04 BST using RSA key ID EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"

* remotes/armbru/tags/pull-qapi-2016-05-12: (23 commits)
  qapi: Change visit_type_FOO() to no longer return partial objects
  qapi: Simplify semantics of visit_next_list()
  qapi: Fix string input visitor handling of invalid list
  tests/string-input-visitor: Add negative integer tests
  qapi: Split visit_end_struct() into pieces
  qmp: Tighten output visitor rules
  qmp: Don't reuse qmp visitor after grabbing output
  spapr_drc: Expose 'null' in qom-get when there is no fdt
  qmp: Support explicit null during visits
  qapi: Add visit_type_null() visitor
  tests: Add check-qnull
  qapi: Document visitor interfaces, add assertions
  qmp-input: Refactor when list is advanced
  qmp-input: Require struct push to visit members of top dict
  qom: Wrap prop visit in visit_start_struct
  qapi-commands: Wrap argument visit in visit_start_struct
  qmp-input: Don't consume input when checking has_member
  qapi: Use strict QMP input visitor in more places
  qapi: Consolidate QMP input visitor creation
  qmp-input: Clean up stack handling
  ...

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