#include <sys/ioctl.h>

(duh)

src/comio/comio_nix.c

@@ -35,6 +35,7 @@
  * Note: If this box doesn't appear square, then you need to fix your tabs.	*
  ****************************************************************************/
 
+#include <sys/ioctl.h>
 #include <sys/file.h>
 #include "comio.h"
 #include "genwrap.h"