Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2020-07-13-tag' into staging

qemu-ga patch queue for hard-freeze

* fix erroneously reporting stale hostname in guest-get-host-name
* fix regression where guest-shutdown asserts when called
* fix race condition with guest-fs-freeze/thaw on w32

# gpg: Signature made Tue 14 Jul 2020 05:47:11 BST
# gpg:                using RSA key CEACC9E15534EBABB82D3FA03353C9CEF108B584
# gpg:                issuer "mdroth@linux.vnet.ibm.com"
# gpg: Good signature from "Michael Roth <flukshun@gmail.com>" [full]
# gpg:                 aka "Michael Roth <mdroth@utexas.edu>" [full]
# gpg:                 aka "Michael Roth <mdroth@linux.vnet.ibm.com>" [full]
# Primary key fingerprint: CEAC C9E1 5534 EBAB B82D  3FA0 3353 C9CE F108 B584

* remotes/mdroth/tags/qga-pull-2020-07-13-tag:
  qga: Use qemu_get_host_name() instead of g_get_host_name()
  util: Introduce qemu_get_host_name()
  qga: fix assert regression on guest-shutdown
  qga-win: Fix QGA VSS Provider service stop failure

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