Merge remote-tracking branch 'remotes/gkurz/tags/for-upstream' into staging

readdir_r() to readdir() conversion, various minor cleanups

# gpg: Signature made Mon 06 Jun 2016 10:52:52 BST
# gpg:                using DSA key 0x02FC3AEB0101DBC2
# gpg: Good signature from "Greg Kurz <gkurz@fr.ibm.com>"
# gpg:                 aka "Greg Kurz <groug@free.fr>"
# gpg:                 aka "Greg Kurz <gkurz@linux.vnet.ibm.com>"
# gpg:                 aka "Gregory Kurz (Groug) <groug@free.fr>"
# gpg:                 aka "Gregory Kurz (Cimai Technology) <gkurz@cimai.com>"
# gpg:                 aka "Gregory Kurz (Meiosys Technology) <gkurz@meiosys.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 2BD4 3B44 535E C0A7 9894  DBA2 02FC 3AEB 0101 DBC2

* remotes/gkurz/tags/for-upstream:
  9p: switch back to readdir()
  9p: add locking to V9fsDir
  9p: introduce the V9fsDir type
  9p: drop useless out: label
  9p: drop useless inclusion of hw/i386/pc.h
  9p/fsdev: remove obsolete references to virtio
  9p: some more cleanup in #include directives

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