audio: pc speaker init fix, rework driver probing
# gpg: Signature made Thu 24 Jan 2019 13:19:52 GMT
# gpg: using RSA key
4CB6D8EED3E87138
# 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/audio-
20190124-pull-request:
audio: probe audio drivers by default
audio: error message tweak
audio: check for pulseaudio daemon pidfile
audio: use try-sdl for openbsd
audio: allow optional audio drivers.
audio: use pkg-config
audio: fix pc speaker init
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>