Merge pull request #35 from google/add-disconnected-state

Add disconnected state
diff --git a/include/oboe/Definitions.h b/include/oboe/Definitions.h
index 341677b..7ec73c0 100644
--- a/include/oboe/Definitions.h
+++ b/include/oboe/Definitions.h
@@ -56,6 +56,7 @@
         Stopped = AAUDIO_STREAM_STATE_STOPPED,
         Closing = AAUDIO_STREAM_STATE_CLOSING,
         Closed = AAUDIO_STREAM_STATE_CLOSED,
+        Disconnected = AAUDIO_STREAM_STATE_DISCONNECTED,
     };
 
     enum class Direction : aaudio_direction_t {