Fix build on freebsd

$FreeBSD: comms/amtterm/files/patch-redir-c 300895 2012-07-14 12:56:14Z beat $
From http://people.freebsd.org/~kib/misc/amtterm.1.patch

1 files changed, 4 insertions, 0 deletions

diff --git a/tcp.c b/tcp.c
index 722abd8..0ee1327 100644
--- a/tcp.c
+++ b/tcp.c
@@ -18,6 +18,10 @@
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <errno.h>