Switch from using 'nacl_main' to 'main' entry point

ports/nethack/nethack_pepper.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <assert.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ skipping 25 matching lines @@
     close(fh);
   }
 
   ret = chdir("/usr/games");
   if (ret != 0) {
     perror("Can change to /usr/games.");
     exit(1);
   }
 }
 
-int nacl_main(int argc, char* argv[]) {
+int main(int argc, char* argv[]) {
   setup_unix_environment(argv[0]);
   return nethack_main(argc, argv);
 }