xwm: dnd does not need cairo-util.h

Turns out dnd.c does not actually need cairo-util.h. This was found when
unifying the include directives of all shared/ headers. Removing this makes one
less place to fix.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

xwayland/dnd.c

@@ -40,7 +40,6 @@
 #include <libweston/libweston.h>
 #include "xwayland.h"
 
-#include "cairo-util.h"
 #include "hash.h"
 
 struct dnd_data_source {