Revert "Linux: change protobuf default option to allow building"

third_party/protobuf/src/google/protobuf/descriptor.proto

 // 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 242 matching lines @@
   // file.  Thus, these types will *not* be nested inside the outer class
   // named by java_outer_classname.  However, the outer class will still be
   // generated to contain the file's getDescriptor() method as well as any
   // top-level extensions defined in the file.
   optional bool java_multiple_files = 10 [default=false];
 
   // If set true, then code generators will store unknown fields so that
   // reserializing a message will retain them. This is the default behaviour
   // unless LITE_RUNTIME is specified. Therefore, this option only makes sense
   // when LITE_RUNTIME is in use.
-  optional bool retain_unknown_fields = 11 [default=true];
+  optional bool retain_unknown_fields = 11 [default=false];
 
   // If set true, then the Java code generator will generate equals() and
   // hashCode() methods for all messages defined in the .proto file. This is
   // purely a speed optimization, as the AbstractMessage base class includes
   // reflection-based implementations of these methods.
   optional bool java_generate_equals_and_hash = 20 [default=false];
 
   // Generated classes can be optimized for speed or code size.
   enum OptimizeMode {
     SPEED = 1;        // Generate complete code for parsing, serialization,
                       // etc.
     CODE_SIZE = 2;    // Use ReflectionOps to implement these methods.
     LITE_RUNTIME = 3; // Generate code using MessageLite and the lite runtime.
   }
-  optional OptimizeMode optimize_for = 9 [default=LITE_RUNTIME];
+  optional OptimizeMode optimize_for = 9 [default=SPEED];
 
 
 
 
   // Should generic services be generated in each language?  "Generic" services
   // are not specific to any particular RPC system.  They are generated by the
   // main code generators in each language (without additional plugins).
   // Generic services were the only kind of service generation supported by
   // early versions of proto2.
   //
@@ skipping 246 matching lines @@
     // end line (optional, otherwise assumed same as start line), end column.
     // These are packed into a single field for efficiency.  Note that line
     // and column numbers are zero-based -- typically you will want to add
     // 1 to each before displaying to a user.
     repeated int32 span = 2 [packed=true];
 
     // TODO(kenton):  Record comments appearing before and after the
     // declaration.
   }
 }