net: use freeaddrinfo() in _info example.

In fact, almost everyone will want to do this, so include the required
headers in net.h.  This makes usage simpler.
Reported-by: Jeremy Visser <jeremy@visser.name>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/net/_info

@@ -15,8 +15,6 @@
  *
  * Example:
  *	#include <ccan/net/net.h>
- *	#include <sys/types.h>
- *	#include <sys/socket.h>
  *	#include <netinet/in.h>
  *	#include <stdio.h>
  *	#include <err.h>
@@ -49,6 +47,7 @@
  *		fd = net_connect(addr);
  *		if (fd < 0)
  *			err(1, "Failed to connect to %s", dest);
+ *		freeaddrinfo(addr);
  *	
  *		if (getsockname(fd, &u.s, &slen) == 0)
  *			printf("Connected via %s\n",

ccan/net/net.c

 /* Licensed under BSD-MIT - see LICENSE file for details */
 #include <ccan/net/net.h>
 #include <ccan/noerr/noerr.h>
-#include <sys/types.h>
-#include <sys/socket.h>
 #include <poll.h>
-#include <netdb.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>

ccan/net/net.h

 /* Licensed under BSD-MIT - see LICENSE file for details */
 #ifndef CCAN_NET_H
 #define CCAN_NET_H
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
 #include <stdbool.h>
 
 struct pollfd;
@@ -16,10 +19,7 @@ struct pollfd;
  * of results, or NULL on error.  You should use freeaddrinfo() to free it.
  *
  * Example:
- *	#include <sys/types.h>
- *	#include <sys/socket.h>
  *	#include <stdio.h>
- *	#include <netdb.h>
  *	#include <poll.h>
  *	#include <err.h>
  *	...
@@ -124,10 +124,7 @@ void net_connect_abort(struct pollfd *pfds);
  * of results, or NULL on error.  You should use freeaddrinfo() to free it.
  *
  * Example:
- *	#include <sys/types.h>
- *	#include <sys/socket.h>
  *	#include <stdio.h>
- *	#include <netdb.h>
  *	#include <err.h>
  *	...
  *	struct addrinfo *addr;