Update protobuf to r428, part 1.

third_party/protobuf/src/google/protobuf/compiler/main.cc

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // http://code.google.com/p/protobuf/
 //
 // 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.
@@ skipping 25 matching lines @@
 #include <google/protobuf/compiler/java/java_generator.h>
 
 
 int main(int argc, char* argv[]) {
 
   google::protobuf::compiler::CommandLineInterface cli;
   cli.AllowPlugins("protoc-");
 
   // Proto2 C++
   google::protobuf::compiler::cpp::CppGenerator cpp_generator;
-  cli.RegisterGenerator("--cpp_out", &cpp_generator,
+  cli.RegisterGenerator("--cpp_out", "--cpp_opt", &cpp_generator,
                         "Generate C++ header and source.");
 
   // Proto2 Java
   google::protobuf::compiler::java::JavaGenerator java_generator;
   cli.RegisterGenerator("--java_out", &java_generator,
                         "Generate Java source file.");
 
 
   // Proto2 Python
   google::protobuf::compiler::python::Generator py_generator;
   cli.RegisterGenerator("--python_out", &py_generator,
                         "Generate Python source file.");
 
   return cli.Run(argc, argv);
 }