Added getter for session Id to AudioSink

Added a method to expose the audio session id at AudioSink interface
so that the AudioPlayer in stagefright can retrieve it.

Also:
- Fixed audio effect send level not being initialized in mediaplayer.
- Fixed compilation error when LOGV is enabled in mediaplayer JNI

Change-Id: I4bb55454fd63d646e0e677692d737c4843fb05fb
diff --git a/include/media/MediaPlayerInterface.h b/include/media/MediaPlayerInterface.h
index 3662983..0521709 100644
--- a/include/media/MediaPlayerInterface.h
+++ b/include/media/MediaPlayerInterface.h
@@ -76,6 +76,7 @@
         virtual uint32_t    latency() const = 0;
         virtual float       msecsPerFrame() const = 0;
         virtual status_t    getPosition(uint32_t *position) = 0;
+        virtual int         getSessionId() = 0;
 
         // If no callback is specified, use the "write" API below to submit
         // audio data.