QAPI patches for 2016-02-19

# gpg: Signature made Fri 19 Feb 2016 10:10:18 GMT 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-2016-02-19:
  qapi: Change visit_start_implicit_struct to visit_start_alternate
  qapi: Don't box branches of flat unions
  qapi: Don't box struct branch of alternate
  qapi-visit: Use common idiom in gen_visit_fields_decl()
  qapi: Emit structs used as variants in topological order
  qapi: Adjust layout of FooList types
  qapi-visit: Less indirection in visit_type_Foo_fields()
  qapi-visit: Unify struct and union visit
  qapi: Visit variants in visit_type_FOO_fields()
  qapi-visit: Simplify how we visit common union members
  qapi: Add tests of complex objects within alternate
  qapi: Forbid 'any' inside an alternate
  qapi: Forbid empty unions and useless alternates
  qapi: Simplify excess input reporting in input visitors
  qapi-visit: Honor prefix of discriminator enum

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