audio: support audio hot-plug event for Windows

audio: support audio hot-plug event for Windows

Because dsound audio doesn't support audio endpoint event,
it has failed to initialize without speaker or mic connection.
Now, dsound supports audio endpoint event.
Therefore, emulator can play sound
even if a speaker is connected to host lately.

- Because the COM initialization requires for each thread,
  in order to share the object, a thread is used as init and event handler.
- When event occurs, the notification callback sends it to init thread.
  If we handle the event in notification callback, it would make deadlock.

Change-Id: Iaeef62d6c5b0952f77f0040abea9bfc7778be536
Signed-off-by: Byeongki Shin <bk0121.shin@samsung.com>