Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2016-10-31-tag' into staging

qemu-ga patch queue for 2.8

* add guest-fstrim support for w32
* add support for using virtio-vsock as the communication channel

# gpg: Signature made Tue 01 Nov 2016 00:55:40 GMT
# gpg:                using RSA key 0x3353C9CEF108B584
# gpg: Good signature from "Michael Roth <flukshun@gmail.com>"
# gpg:                 aka "Michael Roth <mdroth@utexas.edu>"
# gpg:                 aka "Michael Roth <mdroth@linux.vnet.ibm.com>"
# Primary key fingerprint: CEAC C9E1 5534 EBAB B82D  3FA0 3353 C9CE F108 B584

* remotes/mdroth/tags/qga-pull-2016-10-31-tag:
  qga: add vsock-listen method
  sockets: add AF_VSOCK support
  qga: drop unnecessary GA_CHANNEL_UNIX_LISTEN checks
  qga: drop unused sockaddr in accept(2) call
  qga: minimal support for fstrim for Windows guests

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