Adds a --help option and usage message listing all flags to V8.

src/mksnapshot.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 132 matching lines @@
 
 
 int main(int argc, char** argv) {
 #ifdef ENABLE_LOGGING_AND_PROFILING
   // By default, log code create information in the snapshot.
   i::FLAG_log_code = true;
 #endif
   // Print the usage if an error occurs when parsing the command line
   // flags or if the help flag is set.
   int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
-  if (result > 0 || argc != 2 || i::FLAG_h) {
+  if (result > 0 || argc != 2 || i::FLAG_help) {
     ::printf("Usage: %s [flag] ... outfile\n", argv[0]);
     i::FlagList::PrintHelp();
-    return !i::FLAG_h;
+    return !i::FLAG_help;
   }
 
   v8::V8::SetCounterFunction(counter_callback);
   v8::HandleScope scope;
 
   const int kExtensionCount = 1;
   const char* extension_list[kExtensionCount] = { "v8/gc" };
   v8::ExtensionConfiguration extensions(kExtensionCount, extension_list);
   v8::Context::New(&extensions);
 
@@ skipping 10 matching lines @@
   char* str;
   int len;
   ser.Finalize(&str, &len);
 
   WriteInternalSnapshotToFile(argv[1], str, len);
 
   i::DeleteArray(str);
 
   return 0;
 }