Define correct EX_ values if sysexits.h is missing.

@@ -34,24 +34,33 @@
 #include <netdb.h>
 #include "getopt.h"
 
-#ifdef HAVE_SYSEXITS_H
-# include <sysexits.h>
-#endif
-
-#ifndef EX_OK
-# define EX_OK 0
-#endif
-#ifndef EX_UNAVAILABLE
-# define EX_UNAVAILABLE 1
-#endif
-#ifndef EX_TEMPFAIL
-# define EX_TEMPFAIL 2
-#endif
-
 #ifdef HAVE_STRINGS_H
 # include <strings.h>
 #endif
 
+#ifdef HAVE_SYSEXITS_H
+# include <sysexits.h>
+#else
+# define EX_OK          0       /* successful termination */
+# define EX__BASE       64      /* base value for error messages */
+# define EX_USAGE       64      /* command line usage error */
+# define EX_DATAERR     65      /* data format error */
+# define EX_NOINPUT     66      /* cannot open input */
+# define EX_NOUSER      67      /* addressee unknown */
+# define EX_NOHOST      68      /* host name unknown */
+# define EX_UNAVAILABLE 69      /* service unavailable */
+# define EX_SOFTWARE    70      /* internal software error */
+# define EX_OSERR       71      /* system error (e.g., can't fork) */
+# define EX_OSFILE      72      /* critical OS file missing */
+# define EX_CANTCREAT   73      /* can't create (user) output file */
+# define EX_IOERR       74      /* input/output error */
+# define EX_TEMPFAIL    75      /* temp failure; user is invited to retry */
+# define EX_PROTOCOL    76      /* remote error in protocol */
+# define EX_NOPERM      77      /* permission denied */
+# define EX_CONFIG      78      /* configuration error */
+# define EX__MAX        78      /* maximum listed value */
+#endif
+
 #ifndef INADDR_LOOPBACK
 # define INADDR_LOOPBAK 0x7f000001
 #endif