broker: drop unnecessary #include directive

Problem: broker overlay includes ccan/ptrint.h but doesn't use it.

Drop #include directive.

Author: garlick

src/broker/overlay.c

@@ -31,7 +31,6 @@
 #include "src/common/libutil/monotime.h"
 #include "src/common/libutil/errprintf.h"
 #include "src/common/librouter/rpc_track.h"
-#include "src/common/libccan/ccan/ptrint/ptrint.h"
 #include "ccan/array_size/array_size.h"
 
 #include "overlay.h"