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/directory.h

@@ -19,10 +19,7 @@
 #ifndef DIRECTORY_H
 #define DIRECTORY_H
 
-#include "../config.h"
-
 #include "song.h"
-#include "list.h"
 
 typedef List DirectoryList;