Merge remote-tracking branch 'remotes/kraxel/tags/pull-audio-20170301-1' into staging

audio: replay support, sdl2 fix.

# gpg: Signature made Wed 01 Mar 2017 15:38:09 GMT
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/pull-audio-20170301-1:
  audio/sdlaudio: Allow audio playback with SDL2
  audio: make audio poll timer deterministic
  replay: add record/replay for audio passthrough

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