Added some include files in a couple of example programs

This improves portability of the examples.  This patch was
submitted to the OpenBSD ports collection by naddy.

docs/examples/externalsocket.c

@@ -36,6 +36,7 @@
 #else
 #include <sys/types.h>        /*  socket types              */
 #include <sys/socket.h>       /*  socket definitions        */
+#include <netinet/in.h>
 #include <arpa/inet.h>        /*  inet (3) funtions         */
 #include <unistd.h>           /*  misc. UNIX functions      */
 #endif