Create a second copy of the change_notify structure for the hotplug
ao. change_notify->is_hotplug distinguishes the hotplug version from
the regular one monitoring the currently playing ao. Also make the
change notification less verbose now that there might be two of them around.
on changes to PKEY_AudioEngine_DeviceFormat, device status, and default device.
call ao_reload directly in the change_notify "methods".
this requires keeping a device enumerator around for the duration of
execution, rather than just for initially querying devices
Implement skeleton IMMNotificationClient to watch for changes in the
sound device. This will make recovery possible from changes shared
mode sample rate, bit depth, "enhancements"/effects and even graceful
device removal.
http://msdn.microsoft.com/en-us/library/windows/desktop/dd371417%28v=vs.85%29.aspx
Signed-off-by: Kevin Mitchell <kevmitch@gmail.com>