Include what is needed

Remove old includes.
Header files only include other header files that they directly need themselves.

Change-Id: Ic471386808d9f42ea19ccbd59cb50a5f83a89dd0
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 2af162c..33c4462 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -25,6 +25,7 @@
 #include <media/AudioTrack.h>
 #include <utils/Log.h>
 #include <private/media/AudioTrackShared.h>
+#include <media/IAudioFlinger.h>
 
 #define WAIT_PERIOD_MS          10