Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2017-03-06-tag' into staging

Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2017-03-06-tag' into staging

qemu-ga patch queue for 2.9

* fix fsfreeze for filesystems mounted in multiple locations
* fix test failure when running in a chroot
* support for socket-based activation

# gpg: Signature made Mon 06 Mar 2017 07:54:17 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-2017-03-06-tag:
  tests: check path to avoid a failing qga/get-vcpus test
  qga: ignore EBUSY when freezing a filesystem
  qga: add systemd socket activation support

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