Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2015-11-11-tag' into staging

qemu-ga patch queue

* fix for unintended overwriting of data on w32 using
  guest-file-open with append mode

# gpg: Signature made Wed 11 Nov 2015 22:14:52 GMT using RSA key ID F108B584
# 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>"

* remotes/mdroth/tags/qga-pull-2015-11-11-tag:
  qga: fix append file open modes for win32

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