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/Visualizer.cpp b/media/libmedia/Visualizer.cpp
index 5b4071b..e519f13 100644
--- a/media/libmedia/Visualizer.cpp
+++ b/media/libmedia/Visualizer.cpp
@@ -28,6 +28,7 @@
 
 #include <media/Visualizer.h>
 #include <audio_utils/fixedfft.h>
+#include <utils/Thread.h>
 
 namespace android {