Merge remote-tracking branch 'remotes/kraxel/tags/audio-20210316-pull-request' into...

Merge remote-tracking branch 'remotes/kraxel/tags/audio-20210316-pull-request' into staging

coreaudio fixes and cleanups.

# gpg: Signature made Tue 16 Mar 2021 10:47:36 GMT
# gpg:                using RSA key A0328CFFB93A17A79901FE7D4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>" [full]
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>" [full]
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>" [full]
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/audio-20210316-pull-request:
  coreaudio: Handle output device change
  coreaudio: Extract device operations
  coreaudio: Drop support for macOS older than 10.6

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