tcpdump.c: Avoid including two times "netdissect-stdinc.h"

Author: fxlb

tcpdump.c

@@ -140,7 +140,6 @@ The Regents of the University of California.  All rights reserved.\n";
 #include <sys/sysctl.h>
 #endif /* __FreeBSD__ */
 
-#include "netdissect-stdinc.h"
 #include "netdissect.h"
 #include "interface.h"
 #include "addrtoname.h"