Get rid of implicit declaration of function warnings

--- exp_clib.c.orig	Wed Sep  1 00:20:27 2010
+++ exp_clib.c	Sun Apr 28 16:41:29 2013
@@ -14,7 +14,9 @@ would appreciate credit if this program or parts of it
 #  include <inttypes.h>
 #endif
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <sys/ioctl.h>
+#include <unistd.h>
 
 #ifdef TIME_WITH_SYS_TIME
 # include <sys/time.h>
@@ -117,6 +119,7 @@ extern unsigned long	strtoul _ANSI_ARGS_((CONST char *
 #include <tcl.h>
 #include "expect.h"
 #define TclRegError exp_TclRegError
+extern void             exp_init_tty (void);
 
 /*
  * regexp code - from tcl8.0.4/generic/regexp.c
