fix explicit declaration of function openpty

--- pty_termios.c.orig	Fri Aug 27 23:51:53 2010
+++ pty_termios.c	Sun Apr 28 17:04:37 2013
@@ -16,6 +16,8 @@ would appreciate credit if you use this file or parts 
 
 #include "expect_cf.h"
 
+extern char * expErrnoMsg(int);
+
 /*
    The following functions are linked from the Tcl library.  They
    don't cause anything else in the library to be dragged in, so it
@@ -43,6 +45,10 @@ According to Ashley Pittman <ashley@ilo.dec.com>, Digi
 with openpty which supports 4000 while ptmx supports 60. */
 #if defined(HAVE_OPENPTY) && defined(HAVE_PTMX)
 #undef HAVE_PTMX
+#endif
+#if defined(HAVE_OPENPTY) && defined(__OpenBSD__)
+#include <termios.h>
+#include <util.h>
 #endif
 
 #if defined(HAVE_PTYM) && defined(HAVE_PTMX)