Documentation name fixes.

diff --git a/msdos/ioports.c b/msdos/ioports.c
index ec2cb9a..8047b8a 100644
--- a/msdos/ioports.c
+++ b/msdos/ioports.c
@@ -11,6 +11,8 @@
      fix that, I guess.
 */
 
+#include "config.h"
+
 #include <ctype.h>
 #include <stdlib.h>
 #include <stdio.h>