We don't actually have a stdio.h header file. Our printf() functions are

defined in vsprintf.h.  (This may change, since vsprintf.h is a
non-standard name, but for now it's the one to use.)

There should be no need to include vsprintf.h just for DBG() statements,
since include/compiler.h forces it in for a debug build anyway.

src/core/resolv.c

@@ -1,5 +1,4 @@
 #include "resolv.h"
-#include "stdio.h"
 
 static struct resolver resolvers[0] __table_start(resolver);
 static struct resolver resolvers_end[0] __table_end(resolver);