clean up CPP includes

Try to only include headers which are really needed.  We should
particularly check all "headers including other headers".  The
long-term goal is to have a manageable, small API for plugins
(decoders, output) without so many mpd internals cluttering the
namespace.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7319 09075e82-0dd4-0310-85a5-a0d7c8717e4f

src/normalize.c

@@ -16,10 +16,9 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include "normalize.h"
 #include "compress.h"
 #include "conf.h"
-#include "normalize.h"
-#include "os_compat.h"
 
 #define DEFAULT_VOLUME_NORMALIZATION 0