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

- fixes a minor bug that could possibly prevent old guests to remove
  directories
- makes default permissions for new files configurable from the cmdline
  when using mapped security modes
- handle transport errors
- g_malloc()+memcpy() converted to g_memdup()

# gpg: Signature made Thu 29 Jun 2017 14:12:42 BST
# gpg:                using DSA key 0x02FC3AEB0101DBC2
# gpg: Good signature from "Greg Kurz <groug@kaod.org>"
# 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 "[jpeg image of size 3330]"
# 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:
  9pfs: handle transport errors in pdu_complete()
  xen-9pfs: disconnect if buffers are misconfigured
  virtio-9p: break device if buffers are misconfigured
  virtio-9p: message header is 7-byte long
  virtio-9p: record element after sanity checks
  9pfs: replace g_malloc()+memcpy() with g_memdup()
  9pfs: local: Add support for custom fmode/dmode in 9ps mapped security modes
  9pfs: local: remove: use correct path component

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