(difftime) [!HAVE_DIFFTIME]: Define.

(strerror) [!HAVE_STRERROR && !WINDOWSNT]: New.

lib-src/update-game-score.c

 /* update-game-score.c --- Update a score file
-   Copyright (C) 2002 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2003 Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
 
@@ -68,6 +68,11 @@ extern int optind, opterr;
 #define P_(proto) ()
 #endif
 
+#ifndef HAVE_DIFFTIME
+/* OK on POSIX (time_t is arithmetic type) modulo overflow in subtraction.  */
+#define difftime(t1, t0) (double)((t1) - (t0))
+#endif
+
 int
 usage (err)
      int err;
@@ -111,6 +116,23 @@ lose (msg)
 
 void lose_syserr P_ ((const char *msg)) NO_RETURN;
 
+/* Taken from sysdep.c.  */
+#ifndef HAVE_STRERROR
+#ifndef WINDOWSNT
+char *
+strerror (errnum)
+     int errnum;
+{
+  extern char *sys_errlist[];
+  extern int sys_nerr;
+
+  if (errnum >= 0 && errnum < sys_nerr)
+    return sys_errlist[errnum];
+  return (char *) "Unknown error";
+}
+#endif /* not WINDOWSNT */
+#endif /* ! HAVE_STRERROR */
+
 void
 lose_syserr (msg)
      const char *msg;