Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2021-08-09-tag' into staging

Merge remote-tracking branch 'remotes/mdroth/tags/qga-pull-2021-08-09-tag' into staging

qemu-ga patch queue for hard-freeze

* fix memory leak in guest_exec

# gpg: Signature made Tue 10 Aug 2021 02:25:43 BST
# gpg:                using RSA key CEACC9E15534EBABB82D3FA03353C9CEF108B584
# 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-2021-08-09-tag:
  qga: fix leak of base64 decoded data on command error

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