include/denc: remove unnecessary include

Signed-off-by: Max Kellermann <[email protected]>

Author: MaxKellermann

src/include/denc.h

@@ -38,7 +38,6 @@
 #include <boost/container/flat_map.hpp>
 #include <boost/container/flat_set.hpp>
 #include <boost/container/small_vector.hpp>
-#include <boost/intrusive/set.hpp>
 #include <boost/optional.hpp>
 
 #include "include/cpp_lib_backport.h"