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/stats.c

@@ -21,7 +21,6 @@
 #include "directory.h"
 #include "myfprintf.h"
 #include "player.h"
-#include "tag.h"
 #include "tagTracker.h"
 #include "os_compat.h"