add missing headers needed for close() and ioctl().

ok krw@ millert@

src/lib/libutil/opendev.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: opendev.c,v 1.9 2010/06/18 17:03:06 jsing Exp $	*/
+/*	$OpenBSD: opendev.c,v 1.10 2010/06/28 19:12:29 chl Exp $	*/
 
 /*
  * Copyright (c) 2000, Todd C. Miller.  All rights reserved.
@@ -32,7 +32,9 @@
 #include <paths.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
+#include <sys/ioctl.h>
 #include <sys/limits.h>
 #include <sys/disk.h>
 #include <sys/dkio.h>