Linux: change protobuf default option to allow building

remoting/proto/audio.proto

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Protocol for audio messages.
 
 syntax = "proto2";
 
-option optimize_for = LITE_RUNTIME;
-
 package remoting;
 
 message AudioPacket {
   optional int32 timestamp = 1 [default = 0];
 
   // Packets with raw data must have exactly one data field.
   // For those packets, samples are signed and represented using little endian.
   // Some encoders (eg. Speex) may add multiple data fields to separate encoded
   // frames.
   repeated bytes data = 2;
@@ skipping 25 matching lines @@
 
   enum Channels {
     CHANNELS_INVALID = -1;
     CHANNELS_MONO = 1;
     CHANNELS_STEREO = 2;
   }
 
   optional Channels channels = 6 [default = CHANNELS_INVALID];
 }