audio: introduce -audiodev

# gpg: Signature made Tue 12 Mar 2019 07:12:19 GMT
# gpg:                using RSA key 4CB6D8EED3E87138
# 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-20190312-pull-request:
  audio: -audiodev command line option: cleanup
  wavaudio: port to -audiodev config
  spiceaudio: port to -audiodev config
  sdlaudio: port to -audiodev config
  paaudio: port to -audiodev config
  ossaudio: port to -audiodev config
  noaudio: port to -audiodev config
  dsoundaudio: port to -audiodev config
  coreaudio: port to -audiodev config
  alsaaudio: port to -audiodev config
  audio: -audiodev command line option basic implementation
  audio: -audiodev command line option: documentation
  audio: use qapi AudioFormat instead of audfmt_e
  qapi: qapi for audio backends

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

# Conflicts:
#	qemu-deprecated.texi